tag:blogger.com,1999:blog-60940383461730449552024-03-17T23:03:32.347-04:00Parasite of the DaySusan Perkinshttp://www.blogger.com/profile/05944116263349266952noreply@blogger.comBlogger650125tag:blogger.com,1999:blog-6094038346173044955.post-24446341924027641222024-03-09T22:51:00.000-05:002024-03-09T22:51:27.697-05:00Veneriserva pygoclava<div style="text-align: left;"><div>There are many ways to <a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2016.0324">become a parasite</a>, and there are parasites with vastly different ancestries that end up <a href=" https://www.otago.ac.nz/parasitegroup/PDF%20papers/Poulin2011-AdvP.pdf">joining the same path</a> on the road of parasitism. In some cases, sharing the same path can also mean adopting a certain shape. This post is about <i>Veneriserva pygoclava</i>, a worm that lives inside a worm, more specifically it is a <a href="https://en.wikipedia.org/wiki/Polychaete">polychaete worm</a> that has evolved to parasitise another type of polychaete worm which are commonly called "<a href="https://en.wikipedia.org/wiki/Aphrodita">sea mice</a>".</div><div><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSVsQhGNjE96vNIlR0X15e6ZBeW8hkMkvuIny3DWntYi88WGJd5o_liH2FH7JZd40xefFHzVBUU-UATxNcTMTUCFnEyOj0vTTmz0QFgy_nmBwvLCj6uEGn0O-3LOPpZ7KwomKkxRcSQvQWJ5wUT6Ik_U1r4WobT_NaRyiStJZOn-cirYyOpmTiCsoP4v4/s1904/Veneriserva%20pygoclava.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="909" data-original-width="1904" height="306" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSVsQhGNjE96vNIlR0X15e6ZBeW8hkMkvuIny3DWntYi88WGJd5o_liH2FH7JZd40xefFHzVBUU-UATxNcTMTUCFnEyOj0vTTmz0QFgy_nmBwvLCj6uEGn0O-3LOPpZ7KwomKkxRcSQvQWJ5wUT6Ik_U1r4WobT_NaRyiStJZOn-cirYyOpmTiCsoP4v4/w640-h306/Veneriserva%20pygoclava.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Top left: Ventral view of an infected <i>Aphrodita longipalpa </i>with a <i>Veneriserva pygoclava </i>parasite inside. Bottom Left: MicroCT scan image of an <i>Aphrodita longipalpa </i>with <i>Veneriserva pygoclava </i>female highlighted in yellow and juvenile highlighted in blue. Right: A female <i>Veneriserva pygoclava </i>(top) and a male (bottom).<br />Photos from Fig. 1 and Fig. 3 of the paper</td></tr></tbody></table><br /><div>The genus name of this parasitic polychaete translates into "Venus' servant" though this worm is certainly a servant for nobody but itself. You'd think that living inside the body of another animal would restrict how big it can get, but the female <i>Veneriserva</i> grows to about seven centimetres long, which is twice as long as its host. Surprisingly enough, being longer than the host is not unusual among these kinds of <a href=" https://dailyparasite.blogspot.com/2021/02/endovermis-seisuiae.html">parasitic polychaete worms</a>. Despite its size and the amount of space it occupies within the host, it does not seem to cause any injuries or damage to the host's internal organs.</div><div><br /></div><div>Living this endoparasitic lifestyle requires some specialised adaptations, and over the course of its evolution, <i>Veneriserva</i> has ended up with a body plan which is very similar to that of <a href="http://dailyparasite.blogspot.com/search/label/cestode">tapeworms</a>. Despite both being called "worms", tapeworm and polychaete worms are from entirely separate animal phyla and their path to this "tapeworm body plan" (for the lack of a better term) were very different.</div><div><br /></div><div>Tapeworms evolved from free-living flatworms, which are fairly simple animals, at least in terms of their body plan. A flatworm has no body cavity, its gut is more or less a blind-end sac (with some branches in larger flatworms), and it doesn't even have a circulatory system. If anything, in order to adapt to a parasitic lifestyle, tapeworms have evolved to become <b>more complex</b> than their free-living ancestors. Over the course of the tapeworm's evolution, they have gained a new attachment organ - the scolex - which is a <a href=" https://carlzimmer.com/a-tapeworm-mystery-which-way-is-up/">heavily modified head</a>, while the rest of the body has become an efficient conveyor belt of reproductive organs. These parasitic flatworms have even evolved a brand new type of "skin" called a <a href="https://en.wikipedia.org/wiki/Tegument_(helminth)">tegument</a> which allows it to absorb nutrients as well as protect itself against the host's enzymes, and some tapeworms even have the most <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/jmor.21145">complex central nervous system</a> among all the flatworms, enabling them to navigate and maneuver in the dark, fleshy tunnels that are their host's intestinal tract.</div><div><br /></div><div>In contrast, polychaetes are segmented worms, and are actually more similar to us in their body plan, equipped with a full body cavity, muscular gastrointestinal tract, and a closed circulatory system with blood vessels. But <i>Veneriserva</i> has abandoned much of that, because when you're living inside another animal, being built like a tapeworm seems to be the way to go.</div><div><br /></div><div><i>Veneriserva</i> does have a mouth of sorts, but it is not connected to any digestive tract to speak of. In fact, the digestive tract has been reduced down to a throat with a blind-end. Instead, the mouth of <i>Veneriserva</i> serves as a grabber to hold the parasite in place, functioning much like a tapeworm's scolex. Additionally, <i>Veneriserva</i> has also evolved its own version of the tapeworm's tegument, which is covered in fine microscopic finger-like projects (rather like the lining of your small intestine, just inside out) allowing it to absorb nutrients through its skin. There are also patches of cilia on the skin which may serve to stir the host's bodily fluids in order to bring more nutrients into contact with the parasite's skin.</div><div><br /></div><div>However, when it comes to sex, there is one key difference between <i>Veneriserva</i> and tapeworms. Tapeworms are hermaphroditic - any tapeworm can mate with any other individual of the same species, or <a href="https://academic.oup.com/evolut/article/58/11/2591/6755877">even with itself if it is desperate and alone</a>. In contrast <i>Veneriserva</i> have separate female and male sexes which are clearly distinguishable - male worms are tiny compared to their much larger partners (see accompanying photo).</div><div><br /></div><div>This "attachment organ + loads of gonads" type of body plan that tapeworms and <i>Veneriserva</i> have both independently evolved is also found in other internal parasites. For example, <a href=" https://en.wikipedia.org/wiki/Acanthocephala">acanthocephalans</a> - thorny-headed worms - are parasitic worms which live in the gastrointestinal tract of vertebrate animals, and are somewhat related to rotifers. Despite being in a different phylum, they share some key anatomical similarities to tapeworms, with their own version of the tegument, a body dominated by gonads, and a prickly anchor at its "head" to stay attached to the host's intestinal wall. Another example is <i><a href=" https://repository.si.edu/bitstream/handle/10088/8720/SMS-Byrne-1985b.pdf">Thyonicola</a></i>, the parasitic snail which uses a thin stalk to attach itself to the intestines of its sea cucumber host, while the rest of the body is simply a long tube of reproductive organs and developing eggs. There are even some <a href="https://www.sciencedirect.com/science/article/abs/pii/S1055790323001598">parasitic dinoflagellates</a> that have evolved to resemble tapeworms. </div><div><br /></div><div>Judging from how common this "tapeworm-style" anatomy is across different parasite groups, it seems that when you are an internal parasite, you have to get into shape - and that shape happens to be that of a tapeworm.</div><div><br /></div><div>Reference:</div><div><a href="https://link.springer.com/article/10.1007/s13127-023-00633-8">Tilic, E., & Rouse, G. W. (2024). Hardly Venus’s servant—morphological adaptations of <i>Veneriserva</i> to an endoparasitic lifestyle and its phylogenetic position within Dorvilleidae (Annelida). <i>Organisms Diversity & Evolution</i> https://doi.org/10.1007/s13127-023-00633-8</a></div></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-75070793164168114972024-02-12T22:11:00.000-05:002024-02-12T22:11:09.740-05:00Ascarophis globuligera<div style="text-align: left;">To land-dwelling humans, deep sea <a href="https://en.wikipedia.org/wiki/Hydrothermal_vent">hydrothermal vents</a> would seem like a vision of hell, amidst the crushing darkness you have plumes of superheated water, mixed with noxious sulfides, erupting from fissures on the seafloor. But for many deep sea animals, this "hell" is in fact a vibrant oasis in the middle of the abyss. This lively habitat is made possible thanks to <a href="https://ocean.si.edu/ecosystems/deep-sea/microbes-keep-hydrothermal-vents-pumping">bacteria</a> that are able to extract energy from the sulphurous waters billowing from those vents. In the absence of sunlight, these <a href=" https://en.wikipedia.org/wiki/Chemotroph">chemoautotrophs</a> form the <a href=" https://pubmed.ncbi.nlm.nih.gov/18503548/">foundation of the food chain</a>. Some <a href="https://en.wikipedia.org/wiki/Riftia">tube worms</a> have been able to co-opt the power of these bacteria by housing the microbes in their gills, enabling them to grow to enormous sizes. Their tubes form dense, forest-like <a href="https://www.youtube.com/watch?v=JtV-FP212Uc">habitats</a> for many other animals including other polychaete worms, fishes, crustaceans, and molluscs. This sets the stage for all kinds of complex ecological interactions, and that includes <a href=" https://royalsocietypublishing.org/doi/10.1098/rspb.2023.0877">parasitism</a>.</div><div><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBU8g5dMwVybCussSMQ6eyiyAfaAKPMrkyp_e-Gjip0taHPASqFNA83GFBxIUZPm3Hn9JGpUD_nTLXshxoaIHFlh_l0mC-4XFPUIEHrYffUDSgcgTuWx8E2uZuv4OAeysOJdfV42-iMAQstkSxMoxvvZXt8njiPAsN4Q9zq33qW01IinH_ayuZW_h7bMw/s1902/Ascarophis%20globuligera.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1058" data-original-width="1902" height="356" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBU8g5dMwVybCussSMQ6eyiyAfaAKPMrkyp_e-Gjip0taHPASqFNA83GFBxIUZPm3Hn9JGpUD_nTLXshxoaIHFlh_l0mC-4XFPUIEHrYffUDSgcgTuWx8E2uZuv4OAeysOJdfV42-iMAQstkSxMoxvvZXt8njiPAsN4Q9zq33qW01IinH_ayuZW_h7bMw/w640-h356/Ascarophis%20globuligera.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Left: Anterior of <i>Ascarophis globuligera </i>from Fig. 6 of <a href="https://link.springer.com/article/10.1007/s11230-023-10130-3">the paper</a>, Right: Photo of <i><a href="https://fishbase.mnhn.fr/photos/PicturesSummary.php?TRPP=999999&id=48327&what=species&StartRow=&show_all=on">Thermarces cerberus</a></i> (pink vent fish) by Dr <a href="https://scholar.google.com/citations?user=S4VQWCkAAAAJ&hl">Lauren Dykman</a>, used with permission </td></tr></tbody></table><br /><div>This post is about a paper reporting on three newly described species of <i>Ascarophis</i> nematodes that have been found in the guts of some <a href="https://www.fishbase.se/summary/Thermarces-cerberus">deep sea </a><a href="https://fishbase.se/summary/Thermichthys-hollisi.html">hydrothermal vent</a> <a href="https://www.fishbase.se/summary/59415">fishes</a>. Some of those worms were collected as a part of a larger study which focused on looking for parasites <a href=" https://royalsocietypublishing.org/doi/10.1098/rspb.2023.0877">from hydrothermal vent animals</a>, and along with freshly caught specimens, the researchers also examined preserved fishes collected by past expeditions. While they only managed to recover a few specimens of <i>Ascarophis</i> nematodes, some of which were fragmentary, those were enough to provide a scientific description for three different species - <i>A. justinei</i>, <i>A. globuligera</i>, and <i>A. monofilamentosa</i>.</div><div><br /></div><div>The three species differed slightly in which fish species they infect - <i>A. justinei</i> is found in both the <a href=" https://en.wikipedia.org/wiki/Thermarces_cerberus">pink vent fish</a> and a species of <a href=" https://en.wikipedia.org/wiki/Thermichthys_hollisi">viviparous brotula</a>, whereas <i>A. globuligera</i> has only been found in the pink vent fish, and <i>A. monofilamentosa</i> lives in a species of <a href="https://en.wikipedia.org/wiki/Eelpout">zoarchid</a> fish named <i><a href="https://www.fishbase.se/summary/59415">Pyrolycus manusanus</a></i>. While it is not possible to conduct experimental infections to work out exactly how these nematodes transmit between hosts, their life cycles can be inferred based on what is known about other <i>Ascarophis</i> species which are found in shallower waters. This usually involves a <a href="https://meridian.allenpress.com/journal-of-parasitology/article-abstract/86/5/1047/5994/PROPOSED-LIFE-CYCLE-OF-ASCAROPHIS-MARINA-NEMATODA">crustacean</a>, often <a href="https://cdnsciencepub.com/doi/abs/10.1139/f96-329">amphipods</a>, serving as the intermediate host for the parasite's larvae. <a href=" https://www.sciencedirect.com/science/article/abs/pii/0967063794900329">Amphipods are</a> <a href="https://link.springer.com/article/10.1007/s002270000300">plentiful</a> around hydrothermal vents, and these crustaceans are eaten by a range of <a href="https://www.cambridge.org/core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom/article/abs/hydrothermal-vent-octopuses-of-vulcanoctopus-hydrothermalis-feed-on-bathypelagic-amphipods-of-halice-hesmonectes/D99EF5C3157D93B8B0F838596A9CED53">animals</a> including deep sea fishes such as the <a href=" https://www.sciencedirect.com/science/article/pii/S0967063705000130">pink vent fish</a>, making them the ideal vehicle for <i>Ascarophis</i> to complete its life cycle.</div><div><br /></div><div>The need for <i>Ascarophis</i> to reach an amphipod host may explain why each of those <i>Ascarophis</i> species has differently shaped eggs. For example, <i>A. justinei</i> has eggs which are regular, ovoid shape rather similar to other known species of <i>Ascarophis</i>, but the eggs of <i>A. globuligera</i> have a bulge on their side (which gave the species its name), and <i>A. monofilamentosa</i> eggs have a long filament dangling from them which is about fifteen times the length of the egg itself. These differently shaped eggs could mean slightly different transmission strategies. The extra ornament on the eggs of <i>A. globuligera</i> might serve to entice a hungry amphipod by resembling something edible (as with <a href=" https://www.jstor.org/stable/3282479">some tapeworm eggs</a> that infect crustaceans by mimicking diatoms), or in the case of <i>A. monofilamentosa</i>, its long filament may prevent the eggs from drifting away into the empty abyss by wrapping them around a structure, or <a href=" https://www.cambridge.org/core/journals/parasitology/article/production-and-functional-morphology-of-helminth-eggshells/80AF894EDDAAFE93361CDF83115A6969">entangle them</a> around something which might get eaten by an amphipod.</div><div><br /></div><div>Some <i>Ascarophis</i> species are actually known to take a shortcut with their life-cycles - instead of waiting for a fish host to come along, they become sexually mature and <a href="https://dailyparasite.blogspot.com/2012/02/ascarophis-sp.html">start laying eggs inside the amphipod</a>, bypassing the need to enter a fish host to complete their life cycles. It is unknown whether any of the newly described deep sea species are capable of doing this, but in an ephemeral habitat like hydrothermal vents, it would be useful to have such an option as insurance.</div><div><br /></div><div>There are many biomes on this planet which are completely inhospitable to humans. But that does not stop them from being as rich and vibrant as those that we are more familiar with, and wherever there is a thriving ecosystem, you will find parasites taking part in its web of interactions.</div><div><br /></div><div>Reference:</div><div>Moravec, F., Dykman, L. N., & Davis, D. B. (2024). Three new species of <i>Ascarophis</i> van Beneden, 1871 (Nematoda: Cystidicolidae) from deep-sea hydrothermal vent fishes of the Pacific Ocean. <i>Systematic Parasitology</i> <b>101</b>: 2.</div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com1tag:blogger.com,1999:blog-6094038346173044955.post-40891900250575003952024-01-07T18:49:00.000-05:002024-01-07T18:49:57.976-05:00Prosthogonimus cuneatus<div style="text-align: left;"><i>Prosthogonimus</i> is a genus of flukes that live in a special part of a bird's anatomy. It is usually found either in the <a href="https://en.wikipedia.org/wiki/Bursa_of_Fabricius">Bursa of Fabricius</a>, an organ that only birds have, or in the oviduct, and it's this latter location which lend this parasite its common name, the <b>oviduct fluke</b>. This fluke is found all over the world in <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/vms3.1209">many </a><a href="https://www.sciencedirect.com/science/article/abs/pii/S138357691500032X">different </a><a href=" https://www.scielo.br/j/rbzool/a/Nsqx98XgkzgPjk4LbmdcvNR/abstract/?lang=en&format=html">species </a><a href="https://www.cambridge.org/core/journals/journal-of-helminthology/article/morphological-and-molecular-characterization-of-prosthogonimus-falconis-n-sp-trematoda-prosthogonimidae-found-in-a-peregrine-falcon-falco-peregrinus-aves-falconidae-in-the-united-arab-emirates/870E4AD2BC20C4737F1B3253679B00BE">of birds</a>, and while it doesn't seem to cause much issues for wild birds, it presents a major problem for the <a href=" https://poultrydvm.com/pathogens/prosthogonimus-macrorchis">poultry industry</a>.</div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghwELZJzaNQWNiKbq1P-zjDMua8X260AI2G9nIaOakCywJ6J3h7Yqh71ZOKabVwg0fY_jqEkP5HCTeR9Ul1RIixwLuvJyO03B72pPfTu9viPsVtNOfxxy2P36rYrow5BM0qKbldFEd8NTZ5OdZRdAiF6CQIU1Z_frG7A67SZNWWcPY0orYGJ0OxYh5w6Q/s1881/Prosthogonimus%20cuneatus.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1062" data-original-width="1881" height="362" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghwELZJzaNQWNiKbq1P-zjDMua8X260AI2G9nIaOakCywJ6J3h7Yqh71ZOKabVwg0fY_jqEkP5HCTeR9Ul1RIixwLuvJyO03B72pPfTu9viPsVtNOfxxy2P36rYrow5BM0qKbldFEd8NTZ5OdZRdAiF6CQIU1Z_frG7A67SZNWWcPY0orYGJ0OxYh5w6Q/w640-h362/Prosthogonimus%20cuneatus.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Left: Dragonflies <i>Sympetrum vulgatum</i> (top) and <i>Sympetrum depressiusculum</i> (bottom), Right: A metacercaria cyst of <i>Prosthogonimus cuneatus</i>. Photos from Fig. 2 and Fig. 3 of <a href=" https://link.springer.com/article/10.1007/s00436-023-07975-4">the paper</a></td></tr></tbody></table><br /><div style="text-align: left;">Since this fluke lives by clinging to and feeding on the surface of mucosal membranes, its activities can leave <a href=" https://www.jstage.jst.go.jp/article/jvms/64/12/64_12_1129/_article/-char/ja/">lesions and </a><a href="https://www.tandfonline.com/doi/full/10.1080/03079457.2023.2251917">cause inflammations</a>, and heavy infection of <i>Prosthogonimus </i>can lead to all kinds of oviduct disorders in chickens. This includes leaking milky discharges from the cloaca, laying soft-shelled or malformed eggs, or even <a href="https://www.msdvetmanual.com/poultry/disorders-of-the-reproductive-system/egg-peritonitis-in-poultry">egg peritonitis</a>, where egg yolk material gets displaced into the hen's body cavity, leading to secondary infections and death. In some cases, the fluke can even end up getting <a href="https://bioone.org/journals/avian-diseases/volume-64/issue-3/aviandiseases-D-20-00021/Oviduct-Fluke-Prosthogonimus-macrorchis-Found-Inside-a-Chicken-Egg-in/10.1637/aviandiseases-D-20-00021.short">bundled into the egg</a> itself, which seems pretty mild compared with what I have mentioned above, but it would nevertheless be a nasty surprise for anyone looking to make an omelette. To make matters worse, there are currently no effective treatments available for getting rid of this fluke once a bird is infected.</div><div><br /></div><div>So how do birds end up with this peculiar parasite? <i>Prosthogonimus </i>has a multi-host life cycle that takes it across three very different animals - freshwater snails, dragonflies, and birds. In the dragonfly, the larval <i>Prosthogonimus </i>lies in wait as a dormant cyst called a metacercaria, waiting for its host to get eaten by a bird. That is why this parasite is usually associated with free-range chickens, as they have more opportunity to feed on a variety of things. Most studies on <i>Prosthogonimus </i>have focused on the effects it has on the bird hosts, but surprisingly fewer studies have investigated the <i>source</i> of the infection - <b>parasitised dragonflies</b>.</div><div><br /></div><div>To rectify this oversight, a group of researchers undertook a truly herculean effort to investigate the presence of <i>Prosthogonimus </i>in dragonflies from the <a href="https://en.wikipedia.org/wiki/Heilongjiang">Heilongjiang </a>province, China. The researchers collected over TEN THOUSAND dragonflies, composed of 12 different species from 41 locations. They identified each of the dragonflies before dissecting them for <i>Prosthogonimus </i>metacercariae, which are usually located in the abdominal muscles. The researchers noticed that infected dragonflies tend to have softer abdominal muscles, possibly due to injuries caused by the presence of the <i>Prosthogonimus </i>cysts.</div><div><br /></div><div>They found three different species of <i>Prosthogonimus </i>in those dragonflies, of which <i>Prosthogonimus cuneatus</i> was the most common. Overall, about 20% of the dragonflies they examined were infected by <i>Prosthogonimus</i>, but it was more common in some species than others. The spotted darter (<i><a href="https://en.wikipedia.org/wiki/Sympetrum_depressiusculum">Sympetrum depressiusculum</a></i>) was most frequently infected (28.53% prevalence), followed closely by the vagrant darter (<i><a href="https://en.wikipedia.org/wiki/Vagrant_darter">Sympetrum vulgatum</a></i>) (27.86% prevalence) and the autumn darter (<i><a href="https://en.wikipedia.org/wiki/Sympetrum_frequens">Sympetrum frequens</a></i>) (20.99% prevalence). The highest number of fluke larvae in a single dragonfly goes to an unlucky <i>Sympetrum kunckeli</i> which was packed with 157 <i>Prosthogonimus </i>metacercariae in its abdomen.</div><div><br /></div><div>But dragonflies are aerial predators - how do they end up being infected with fluke larvae which are shed from freshwater snails? Well, before becoming acrobatic flying hunters, dragonflies spend their early life as underwater predators. But this aquatic life also expose them to <i>Prosthogonimus</i>' waterborne larvae, which are drawn into the dragonfly nymph's body through its respiratory current - in other words, they get <a href="https://core.ac.uk/download/pdf/222896568.pdf">sucked through the dragonfly nymph's butt</a> whenever it takes a breath. Even as the dragonflies metamorphose into airborne adults, they carry the legacy from their youth in the form of <i>Prosthogonimus </i>cysts</div><div><br /></div><div>Overall, the study found that <i>Prosthogonimus </i>was most common in <a href="https://en.wikipedia.org/wiki/Heihe">Heihe</a>, which might be due to the presence of large wetlands in the area. Those wetlands are home to high levels of biodiversity which help support the life cycle of this parasite - they provide habitats for numerous snails that can host the asexual stage of <i>Prosthogonimus</i>, along with wild birds that would usually act as the final host for this parasite. Just add dragonflies, which are always common around water bodies, and the circle of life is complete for <i>Prosthogonimus</i>.</div><div><br /></div><div>Studying and elucidating the life cycles and ecological role of parasites in their natural context is an important part of disease ecology research. Understanding what these parasites actually do in nature can help us prevent them from causing problems in the animals that we raise.</div><div><br /></div><div>Reference:</div><div>Li, B., Lan, Z., Guo, X. R., Zhang, A. H., Wei, W., Li, Y., Jin, Z. H., Gao, Z. Y., Zhang, X. G., Li, B., Gao, J. F., & Wang, C. R. (2023). Survey of the <i>Prosthogonimus </i>spp. metacercariae infection in the second intermediate host dragonfly in Heilongjiang Province, China. <i>Parasitology Research</i> <b>122</b>: 2859-2870.</div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com1tag:blogger.com,1999:blog-6094038346173044955.post-25913453242970858182023-12-14T20:32:00.000-05:002023-12-14T20:32:16.995-05:00Euglenaformis parasitica<div style="text-align: left;">This parasite is invisible to the naked eye, can kill its host in 3 days, and it can be found lurking in the waters of rice fields. What I have just described may sound like a nightmare pathogen from a b-horror movie, but it is actually a microscopic flagellated protozoan that has given up a solar-powered life for one fuelled by the blood of its victims. The name of this microscopic monster is <i>Euglenaformis parasitica</i>, and it belongs to a group of otherwise innocuous single-celled critters called <a href="https://en.wikipedia.org/wiki/Euglenid ">Euglenids</a>.</div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8CijUQDYdZNQJ85kxqQFmjAQRgJQKMB4dIv5eZKldJQznHwsld056pjUtUb9aFycaXL5dEviTof7CRh9GK24gsMpnYqGaVQiq7yDCuHBZTfon6yIVtChMuEq3PtKzCoAHg1LiZM_kSgBR5ZUCpN91uXlrjC7lCsw6Qe2GUhSxtyk_ZTm9muHwZ4b1T44/s1311/Euglenaformis%20parasitica.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1067" data-original-width="1311" height="520" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8CijUQDYdZNQJ85kxqQFmjAQRgJQKMB4dIv5eZKldJQznHwsld056pjUtUb9aFycaXL5dEviTof7CRh9GK24gsMpnYqGaVQiq7yDCuHBZTfon6yIVtChMuEq3PtKzCoAHg1LiZM_kSgBR5ZUCpN91uXlrjC7lCsw6Qe2GUhSxtyk_ZTm9muHwZ4b1T44/w640-h520/Euglenaformis%20parasitica.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Left: Scanning electron micrograph of <i>Euglenaformis parasitica. </i>Top Right: <i>E. parasitica </i>extracted from an ostracod host. Bottom Right: <i>E. parasitica </i>visible in the appendage of an infected ostracod.<br />Photos from Fig. 1 and Fig. 7 of <a href="https://www.sciencedirect.com/science/article/pii/S1434461023000299">the paper</a></td></tr></tbody></table><br /><div>Euglenids are single-celled flagellated organisms often found in freshwater. The most well-known and well-studied genus is <i><a href=" https://en.wikipedia.org/wiki/Euglena">Euglena</a></i>, which is literally the textbook example of the group, appearing in many biology books as an example of a single-celled eukaryote organism. Many euglenids are photosynthetic, and <a href="https://en.wikipedia.org/wiki/Euglenozoa">historically</a> they have been treated as sharing affinity with plants (due to their photosynthetic capabilities) or with animals (due to their active flagellum and being able to take in nutrient via <a href="https://en.wikipedia.org/wiki/Heterotroph">heterotrophy</a>), before getting shunted into a group called the "<a href="https://en.wikipedia.org/wiki/Protist">protist</a>" which is just a jumble of different organisms that scientists couldn't classify into plants, animals, or fungi.</div><div><br /></div><div><i>Euglena</i> and its kin are mostly free-living, photosynthesizing when the sun's out, absorbing organic matter from the environment when it's dark. But the ancestor of <i>E. parasitica</i> was not content with this mostly peaceful lifestyle, and has evolved to live inside the body of animals. These euglenids were found parasitising <a href="https://en.wikipedia.org/wiki/Ostracod">ostracods</a> (also known as seed shrimps) and <a href="https://en.wikipedia.org/wiki/Rhabdocoela">flatworms</a> in a rice field in Ibaraki, Japan. Ostracods and flatworms belong to two entirely different phyla of animals, and most parasites that infect different phyla of host animals do so at different stages of their complex, multi-stage life cycles. But <i>E. parasitica </i>has just a simple life cycle, which makes it quite remarkable that it is able to adapt to the very different internal environments presented by ostracods and flatworms.</div><div><br /></div><div>When <i>E. parasitica</i> is in an ostracod, it dwells in the body cavity, swimming in the hemolymph and bathing in its nutrients. Whereas in flatworms, since they don't have any body cavities to speak of, <i>E. parasitica</i> lives in the space between the spongy tissue that forms the bulk of a flatworm's body, burrowing between the cells of the <a href="https://en.wikipedia.org/wiki/Parenchyma#Flatworms">parenchymal tissue</a>. But whether it is in an ostracod or a flatworm, once <i>E. parasitica</i> establishes itself in the host's body, it starts absorbing the literal lifeblood of their host, using it to fuel its exponential growth as it divides and conquers from within. </div><div><br /></div><div>What started with just a single or a few <i>E. parasitica</i> soon turns into a swarm. This is particularly noticeable in flatworms - uninfected flatworms are semi-translucent, but infected flatworms darken in colour as their body becomes filled with brownish to blackish granules which are actually rapidly dividing <i>E. parasitica</i>. The same goes for ostracods as their blood becomes saturated with the parasite's progenies. After three days, the insides of the host are completely consumed by the swarm of <i>E. parasitica</i>, which proceeds to exit into the surrounding water, leaving behind an empty husk. </div><div><br /></div><div>There are still a lot of mysteries surrounding this flagellated organism, such as how it is able to make use of such radically different hosts as flatworms and seed shrimps, or how it enters the host's body in the first place. Does it somehow bore through the body wall, or perhaps it tricks the host into eating it, and then burrows through the digestive tract to other parts of the body? If so, it won't be the only <a href=" https://dailyparasite.blogspot.com/2010/11/november-26-genarchella-astyanactis.html">parasite to </a><a href=" https://dailyparasite.blogspot.com/2010/07/july-28-galactosomum-bearupi.html">use that trick</a>. There are also questions about its evolutionary origin. <i>Euglenaformis parasitica</i>'s close relatives are photosynthetic euglenids, so what made it abandon a solar-powered life in favour of living and reproducing in the bodies of small aquatic animals? Understanding that process would provide us with another clue as to how various different organisms ending up following the path of parasitism.</div><div><br /></div><div>Reference:</div><div>Kato, K., Yahata, K., & Nakayama, T. (2023). Taxonomy of a New Parasitic Euglenid, <i>Euglenaformis parasitica</i> sp. nov.(Euglenales, Euglenaceae) in Ostracods and Rhabdocoels. <i>Protist </i><b>174</b>: 125967.</div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-79086066706967850172023-11-14T19:15:00.000-05:002023-11-14T19:15:46.533-05:00Stylops ater<div style="text-align: left;"><a href="https://en.wikipedia.org/wiki/Strepsiptera">Strepisptera</a> is an order of parasitic insects with some very unique characteristics.They are also known as twisted wing parasites, based on the twisted hindwings on the male parasite. They infect <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev.ento.54.110807.090525">many different orders</a> of insects, but mostly target wasps and bees where they up take up residency in the host's abdomen. If you know what to look for, you can immediately spot their presence. In fact, there's even a special term for describing bees and wasps that are parasitised - they get "stylopized".</div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUUWCPF2WuUypSl1kSrMepJoZHpW2UVZFwgqeXlajwjosZxiNWRbAy10TD6AmBIjGQ3uU66x316_ZVJ45j7T34bdU9_QmB73LThOmnIH-dmHiEjqXf9eZXwacS0EzCw0SO3WHYe2Ger_7KDptF6Wr7jBf-yxoefhq3BfPSjcY8FstqstWCLeEZDJHPgKI/s1236/Stylops%20ater.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1236" data-original-width="1077" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUUWCPF2WuUypSl1kSrMepJoZHpW2UVZFwgqeXlajwjosZxiNWRbAy10TD6AmBIjGQ3uU66x316_ZVJ45j7T34bdU9_QmB73LThOmnIH-dmHiEjqXf9eZXwacS0EzCw0SO3WHYe2Ger_7KDptF6Wr7jBf-yxoefhq3BfPSjcY8FstqstWCLeEZDJHPgKI/w558-h640/Stylops%20ater.png" width="558" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Top: A male <i>Stylops ater </i>(indicated by red arrow) attempting to mate with a female in a bee's abdomen. <br />Bottom left: Female <i>Stylops ater </i>adult (indicated by red arrow) in a bee's abdomen, <br />Bottom right: Male <i>Stylops ater</i> pupa casing (indicated by red arrow) in a bee's abdomen. <br />From Fig. 1 of the paper</td></tr></tbody></table><br /><div>And it's not just the hindwings of stresipterans that are a bit twisted, these insects have extreme sexual dimorphism, so much so that if you didn't know any better, you'd think the females and males are completely different types of animals. The female stresipteran looks like a grub, and she spends her entire life inside the abdomen of the host, with just her head partially poking out from between the segments of the host's abdomen.</div><div><br /></div><div>In contrast, the males have a pair of giant compound eyes, prominent branched antennae and the "twisted wings" that give this group of insects its name. They have a short and frantic adulthood - after emerging from the host, he only lives for a few hours and his sole mission in life is to find and mate with an elusive female strepisteran, hidden away in the abdomen of a host insect. And he does the deed with an appendage that entomologist Tom Houslay once vividly called a "<a href="https://tomhouslay.com/2014/12/30/twisted-wings-twisted-sex/">stabby cock dagger</a>". The technical term for this form of mating is "hypodermic insemination" - where the male basically stabs and inject his sperm into the female, and the sperm somehow find their way to the eggs. Strespiterans are not alone in having this type of appendage, <a href=" https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1691516/">male bed bugs</a> also have a stabby cock dagger - but that's another story.</div><div><br /></div><div>The study being featured in this post focuses on <i>Stylops ater</i>, a species which parasitises <i>Andrena vaga</i>, the <a href=" https://en.wikipedia.org/wiki/Andrena_vaga">grey-backed mining bee</a>. Unlike the honeybees that most people are familiar with, these are solitary bees, with no castes. And while they do gather into an aggregation to nest, each bee just builds and looks after their own nest. The researchers examined a population of these bees in Lower Saxony, Germany. They sampled over two periods, during late winter, when all 508 bees they looked at were stylopized, and late spring, when they only managed to find two stylopized bees out of a total of 150.</div><div><br /></div><div>Almost two-third of the stylopized bees were female, but these parasites seem to prefer hosts that are of the same sex as themselves. Since female bees live longer and can provide more nutrients than male bees, this works out well for the life history of female <i>Stylops</i> as it gives them more time and nutrients to grow her brood. After mating, the female <i>Stylops</i> can release up to 7000 offspring, which crawl off to find other bees. While each larva is merely 0.2 millimetre long, they can traverse long distances by hitching a ride on the hair, pollen sacks, or even the crop of bees, to end up in a new bee nest, filled with fresh hosts.</div><div><br /></div><div>While most bees only hosted a single parasite, some had two or three, and the researchers did find one very unlucky bee that was harbouring <b>four</b> <i>Stylops</i> in its abdomen. But even a single <i>Stylops</i> can take a severe toll on its host. In fact, this parasite is so demanding that it wouldn't grow as big if it had to share its host with another <i>Stylops</i>. As a result, bees infected with <i>Stylops</i> are unable to develop eggs or only produce poorly developed eggs.</div><div><br /></div><div>But aside from effectively sterilising the bee, <i>Stylops</i> also tinkers its host's biological clock, making it emerge out of hibernation a few weeks earlier than uninfected bees - hence why the researchers found so many stylopized bees in late winter. Making the bees such early risers ensures that there will be plenty of female <i>Stylops</i> around for the male <i>Stylops</i> to find, which will be emerging at that time to live out their extremely short lives. It also gives the female <i>Stylops</i>' larvae more time to develop, so they will be able to crawl off in time to find new hosts in the bee's brood cells. This type of behaviour manipulation is comparable to what's found in <i><a href=" https://dailyparasite.blogspot.com/2013/10/sphaerularia-vespae.html">Sphaerularia vespae</a></i>, a nematode that alters the seasonal biological clock of hornet queens.</div><div><br /></div><div>In order to make these changes to the bee's internal clock, <i>Stylops</i> would have to manipulate the host's hormones, but this also results in some side effects on the bee's body. Female bees that get stylopized tend to have a hairier back, skinnier legs, and the hairs on said legs become shorter and more sparse. In short, they take on characteristics that are more similar to that of regular male bees.</div><div><br /></div><div>So next time you are out and about, keep an eye out for a bee that looks a bit different from the rest. It might be flying under the influence of a parasite tucked away in its abdomen, looking to make a rendezvous with her short-lived partner.</div><div><br /></div><div>Reference:</div><div><a href="https://www.cambridge.org/core/journals/parasitology/article/anatomical-phenological-and-genetic-aspects-of-the-hostparasite-relationship-between-andrena-vaga-hymenoptera-and-stylops-ater-strepsiptera/3A0EC2A300793A0274010771C5DB1ABF">Hoffmann, M., Gardein, H., Greil, H., & Erler, S. (2023). Anatomical, phenological and genetic aspects of the host–parasite relationship between <i>Andrena vaga</i> (Hymenoptera) and <i>Stylops ater</i> (Strepsiptera). <i>Parasitology</i> <b>150</b>: 744-753</a></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-42800299816963162702023-10-10T21:36:00.000-04:002023-10-10T21:36:14.308-04:00Atriophallophorus winterbourni<div style="text-align: left;"><div>In <a href=" https://en.wikipedia.org/wiki/Lake_Alexandrina_(New_Zealand)">Lake Alexandrina</a> of New Zealand lives a species of tiny freshwater snail called <i><a href=" https://en.wikipedia.org/wiki/New_Zealand_mud_snail">Potamopyrgus antipodarum</a></i>. These snails are capable of alternating between sexual and asexual reproduction and can be extremely abundant. So much so that they have become <a href="https://invasions.si.edu/nemesis/species_summary/205006">invasive</a> in many other parts of the world. Outside of their original home, they are free to proliferate to their heart's content. But back in New Zealand, these snails don't always have things go their way. They are held back by a whole menagerie of flukes which parasitise them - at least <a href="https://www.mapress.com/zt/article/view/zootaxa.3418.1.1">20 different species</a> in fact.</div><div><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiP7UxQGZEm76n8vrYt81eAQ3VNvST-NqzLhJfVyRRD3efnggh0BSM-57-rNe6AS7ATY4D-r0uV_DYZqvPkMSAlUBI2IzoGBRSka4iVkxUDg8B6s7KFVkoTmc7JLXLX6fPI1Pq3wCaAkPJq86OXXL2RMToQnVoCwORQBQq23cfFasDIeeWvWjmYngy1nos/s1156/Atriophallophorus%20winterbourni.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1156" data-original-width="1074" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiP7UxQGZEm76n8vrYt81eAQ3VNvST-NqzLhJfVyRRD3efnggh0BSM-57-rNe6AS7ATY4D-r0uV_DYZqvPkMSAlUBI2IzoGBRSka4iVkxUDg8B6s7KFVkoTmc7JLXLX6fPI1Pq3wCaAkPJq86OXXL2RMToQnVoCwORQBQq23cfFasDIeeWvWjmYngy1nos/w594-h640/Atriophallophorus%20winterbourni.png" width="594" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Top: Photo of the snail <i>Potamopyrgus antipodarum</i> by Michal Maňas, used under Creative Commons (CC BY-SA 4.0) license. Bottom: The metacercariae cysts of <i>Atriophallophorus winterbourni</i>, from Figure 1 of the paper.</td></tr></tbody></table><br /><div>These flukes have a range of different life cycles, but all of them use <i>P. antipodarum</i> as a site of asexual reproduction - converting the snail's insides into a clone factory and rendering it sterile in the process. These flukes might be the reason why these snails continue to <a href=" https://royalsocietypublishing.org/doi/full/10.1098/rsbl.2013.1091">engage in sex</a> every now and then, despite asexual reproduction being much more efficient. Sex is necessary to maintain genetic variations - the key ingredient in the evolutionary arms race against all those flukes.</div><div><br /></div><div>Researchers who have been studying these snails and their flukes noticed that while all 20 species of those parasite are essentially body snatchers that take over the insides of their unwitting host, one species - <i>Atriophallophorus winterbourni</i> - goes beyond simply messing with their host's physiology and seems to be influencing the snail's behaviour too. Snails infected with <i>A. winterbourni</i> tend to be found in the shallow areas of the lake. Among snails collected from the shallow water margin of the lake, they represent 95% of the infections. Is this because those areas just happen to be hot spots for snails to get infected with <i>A. winterbourni</i>? Or are these flukes actually coaxing the snails into hanging out in the shallows?</div><div><br /></div><div>To figure out if there's something special about <i>A. winterbourni</i>, researchers compared snails infected with <i>A. winterbourni</i> with those that were infected with a different species of fluke - <i>Notocotylus</i> - to see if such behavioural change is simply a side-effect of fluke infection, or if it is something specific to <i>A. winterbourni</i>. The researchers did this by setting up a series of ten 5 metres long tubular mesh cages that stretched across different depth clines in the lake, from less than 0.8 metres at the shallow end to 2.8 metres at the deep end, with different sections of the cage corresponding to different levels of water depth. Using snails collected from two high infection prevalence sites at the lake, they added about 800 snails to the deepest section of each cage, and the snails were allowed to freely roam between the different sections. After eleven days, samples of snails were randomly collected from each depth level and examined for parasites.</div><div><br /></div><div>There are some key differences in the life cycles of <i>A. winterbourni</i> and <i>Notocotylus</i> that makes them good for comparisons. Just like other flukes, <i>A. winterbourni</i> undergoes asexual reproduction inside the snail host, producing a whole load of clonal larvae. But unlike many other flukes, these clonal larvae <i>stay</i> in the snail and transform into cysts, where they wait to be eaten by a duck hungry for snails. In contrast, snails that are infected with <i>Notocotylus</i> release those clonal larvae into the surrounding waters, and they do so continuously over the course of about 8 months. These larvae attach themselves to vegetation or the shells of other snails, and are transmitted to grazing ducks that accidentally ingest them. Therefore, unlike <i>A. winterbourni</i>, their transmission is largely decoupled from the snail's own movement and behaviour.</div><div><br /></div><div>So after those eleven days of allowing infected snails to roam in the cages, what did the researchers find? Well, snails infected with <i>A. winterbourni</i> were heavily distributed towards the shallow end, with over a third of the snails in that section being infected, which is <b>over three times higher</b> than the expected background infection level (11%). In the deepest section of the cage, <i>A. winterbourni</i>-infected snails were rare, representing only 3-5% of the snails in that section, and some of them were immature infections. In contrast, those infected with <i>Notocotylus</i> were found to have distributed themselves fairly evenly across the entire depth cline. It is unclear what exactly <i>A. winterbourni</i> is doing to the snails that makes them favour shallow water, but more importantly, <b>why</b> would they do this? What's in it for the fluke? Well, the final hosts for <i>A. winterbourni</i> are dabbling ducks that only feed in the shallow parts of the lake. So in order for <i>A. winterbourni</i> to make a successful rendezvous with its final host and complete its life cycle, it will have to prod its snail host into the shallows.</div><div><br /></div><div><i>Atriophallophorus winterbourni</i> belong to a family of flukes called <b>Microphallidae</b>, and there are a few other species in this family which are also known host manipulators. For example, <i>Gynaecotyla adunca</i> is a species that infects marine mudsnails, and it coaxes its mudsnail host <a href=" https://www.science.org/doi/10.1126/science.3823901">into stranding itself</a> onto beaches, which brings them closer to the crustaceans that serve as the next host in the parasite's life cycle. There's also <i>Microphallus papillorobustus</i>, which infects little sand shrimps (amphipods), and it <a href="https://www.parasite-journal.org/articles/parasite/abs/1984/01/parasite1984591p41/parasite1984591p41.html">alters their behaviour</a> <a href=" https://www.frontiersin.org/articles/10.3389/fevo.2015.00109/full">in a number of different ways</a> that makes them more visible to hungry birds. Even though not all members of Microphallidae are host manipulators, it's a trait that does seem pretty common in this fluke family. Sometimes, in order to complete a life cycle, you just have to drag that snail to where you need it to be.</div><div><br /></div><div>Reference:</div><div><a href=" https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.10124">Feijen, F., Buser, C., Klappert, K., & Jokela, J. (2023). Parasite infection and the movement of the aquatic snail <i>Potamopyrgus antipodarum</i> along a depth cline. <i>Ecology and Evolution</i> <b>13</b>: e10124.</a></div></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-21303348248696528362023-09-08T21:27:00.001-04:002023-09-09T03:20:52.277-04:00Rhizolepas sp.<div style="text-align: left;">Parasitism has evolved a few different times in barnacles. Most parasitic barnacles belong to a group called the <b>rhizocephalans</b>, which are <a href=" https://theconversation.com/the-crab-castrating-parasite-that-zombifies-its-prey-27200">body-snatchers</a> of <a href="https://dailyparasite.blogspot.com/2016/10/peltogaster-sp.html">decapod crustaceans</a> <a href="https://dailyparasite.blogspot.com/2016/02/briarosaccus-regalis.html">like crabs</a> <a href="https://dailyparasite.blogspot.com/2017/09/sylon-hippolytes.html">and shrimps</a>. Aside from them, there are two other known genera of parasitic barnacles: <i><a href=" https://dailyparasite.blogspot.com/2014/09/anelasma-squalicola-revisited.html">Anelasma squalicola</a></i> - which is the bane of deep sea Squaliform sharks, and then there's the barnacle being featured in today's post - <i>Rhizolepas</i>, a rare little crustacean that parasitises seafloor-dwelling <a href="https://en.wikipedia.org/wiki/Polynoidae">aphroditid scale worms</a>. Both of them belong to a group called <b>Thoracicalcarea</b>, which happens to be a sister group to the rhizocephalans.</div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTEM453AeplyBVJbUBvoxgjJjIzydT0EkJ883u9XCjqWKvEs4q_DoKRKBd9JCZq7WVGFRW9FCMt6zT4yB1hC-z4EMmAKJMWpAvKWzU3Mqa-29SJmFkj82HPNhPPZy4O2VUo7Ti8cdO2NrojKGq_z1AYmcZHCiU4c0cdnWo-IXL-tHLb7cjIvRLHh6GN64/s2026/Rhizolepas.jpg" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1456" data-original-width="2026" height="460" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTEM453AeplyBVJbUBvoxgjJjIzydT0EkJ883u9XCjqWKvEs4q_DoKRKBd9JCZq7WVGFRW9FCMt6zT4yB1hC-z4EMmAKJMWpAvKWzU3Mqa-29SJmFkj82HPNhPPZy4O2VUo7Ti8cdO2NrojKGq_z1AYmcZHCiU4c0cdnWo-IXL-tHLb7cjIvRLHh6GN64/w640-h460/Rhizolepas.jpg" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Left: <i>Rhizolepas in situ</i> attached to its scale worm host. Right: <i>Rhizolepas </i>removed from the host, showing its entire anatomy.<br />Photos from Figure 1 of the paper.</td></tr></tbody></table><br /><div><i>Rhizolepas</i> has a general shape that broadly resembles typical stalked barnacles that can be found attached to piers or drifting debris, but it lacks the feeding legs that those barnacles use to filter food particles out of the water. Instead, it has a dense network of roots at its base that extend deep into the host's body which it uses to suck up nutrients directly from the host.</div><div><br /></div><div>This blog post covers a recent study on <i>Rhizolepas</i>, and it's about time too because the last time anyone managed to collected a specimen of this little barnacle was <a href="https://www.jstor.org/stable/20102971">back in 1960</a>. The <i>Rhizolepas</i> specimen in this study was collected during a trawl in the seas off Kagoshima, southern Japan. Out of the ten <i>Laetmonice</i> scale-worms that were collected by the trawl, only ONE of them was infected with <i>Rhizolepas</i>. This provided an amazing opportunity to find out more about this rare little barnacle, so the scientists carefully removed the barnacle from its scale worm host and preserved it in high-grade ethanol for further DNA analyses.</div><div><br /></div><div>How did <i>Rhizolepas</i> get to be the way it is now? Looking at its morphology is of relatively limited value - evolving towards parasitism does weird things to an organism's body. It is a process that turns copepods into <a href="https://dailyparasite.blogspot.com/2022/06/sarcotaces-izawai.html">fleshy blobs</a>, and transform <a href="https://invertebase.org/stri/taxa/index.php?tid=6707">snails into sausages</a>. So trying to work out the evolutionary origin of something like <i>Rhizolepas</i> based on its anatomy is an exercise in futility. But while its anatomy may have been modified beyond recognition, its evolutionary history is recorded in its DNA.</div><div><br /></div><div>DNA analysis revealed that <i>Rhizolepas</i>' closest relatives are <i>Octolasmis</i> - a genus of goose barnacles that spend their lives attached to all kinds of different animals, including the <a href="https://www.tandfonline.com/doi/abs/10.1080/00785326.1989.10430850">shells and</a> <a href="https://academic.oup.com/jcb/article/35/2/159/2547880">gills of crabs</a> and the <a href=" https://www.jstor.org/stable/20103432">skin of sea snakes</a>. The study also found another barnacle called <i>Rugilepas</i>, is actually nested among the various species of <i>Octolasmis</i>, and it provides a perfect transitional model for how <i>Rhizolepas</i> might have evolved from a regular stalked barnacle into a fully committed parasite.</div><div><br /></div><div><i>Rugilepas</i> lives on sea urchins, but they don't simply attach to their host, their presence <a href=" https://www.sciencedirect.com/science/article/pii/S2589004220300699">induces a gall</a> on the sea urchin's body which snugly encases the barnacle. However, unlike <a href=" https://dailyparasite.blogspot.com/2017/08/sabinella-troglodytes.html">other gall-inducing animals</a> in sea urchins, <i>Rugilepas</i> is walled off from the urchin's internal anatomy, and doesn't draw any nutrients from its host. Furthermore, while its feeding limbs are significantly reduced, they are not completely useless like those in <i>Rhizolepas</i> and <i>Anelasma</i>. So between <i>Octolasmis</i> and <i>Rugilepas</i>, we can get an ideal of the evolutionary steps that <i>Rhizolepas</i> might have taken on its path to becoming a parasite of scale worms</div><div><br /></div><div>Based on its level of DNA divergence from other barnacles, <i>Rhizolepas</i> is estimated to have originated about 19 million years ago, during the <a href="https://en.wikipedia.org/wiki/Miocene">Miocene</a>. Given the external part of this barnacle no longer performs its ancestral function of feeding, the potential next step in their evolution would be to get rid of any dangly parts altogether, and become completely internalised within the host like their rhizocephalan cousins.</div><div><br /></div><div>Barnacles are particularly pre-adapted for flirting with or even becoming completely committed to a parasitic lifestyle. Even among non-parasitic barnacles, these crustaceans are remarkably versatile in attaching to different living substrates, from <a href=" https://royalsocietypublishing.org/doi/full/10.1098/rspb.2020.0300">sponges</a> and <a href="https://academic.oup.com/evolut/article/76/1/139/6728556">corals</a>, to <a href=" https://www.researchgate.net/publication/342089631_How_whale_and_dolphin_barnacles_attach_to_their_hosts_and_the_paradox_of_remarkably_versatile_attachment_structures_in_cypris_larvae">whales</a> and <a href="https://www.frontiersin.org/articles/10.3389/fevo.2021.807237/full">turtles</a>. Perhaps this versatility gives barnacles an advantage in taking the next step from a mere hitch-hiker into a full-blown parasite. Since the oldest known barnacles date back to the <a href="https://academic.oup.com/zoolinnean/article/193/3/789/6149353">mid-Carboniferous period</a> around 330 million years ago, who knows what other marine animals they might have attached to or even parasitised throughout Earth's history?</div><div><br /></div><div>Reference:</div><div><a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2022.0550">Watanabe, H. K., Uyeno, D., Yamamori, L., Jimi, N., & Chen, C. (2023). From commensalism to parasitism within a genus-level clade of barnacles. <i>Biology Letters</i> <b>19</b>: 20220550.</a></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-10163814111170594302023-08-10T23:47:00.000-04:002023-08-10T23:47:14.646-04:00Bothrigaster variolaris<div style="text-align: left;"><i>Student guest post time! One of the assessments that I set for students in my ZOOL329 Evolutionary Parasitology class is for them to summarise and write about a paper that they have read in the manner of a blog post. The best blog posts from the class are selected for re-posting (with their permission) here on the Parasite of the Day blog. So from the class of 2023, here’s a post by Nikita Sheelah, about a bird of prey with too many flukes.</i></div><div><br /></div><div>To dare to do what hasn’t been done before has been the driving force behind many advancements in society, such as the creation of <a href="https://en.wikipedia.org/wiki/Variolation">vaccines</a>, <a href=" https://en.wikipedia.org/wiki/Katsud%C5%8D_Shashin">anime</a>, or the ground-breaking <a href=" https://en.wikipedia.org/wiki/H._B._Reese">Reese’s Peanut Butter Cups</a>. Being the first in recorded history to do something different essentially immortalises people in the history books, which often carries incredible pride and achievement. This seems to be the case for a group of trematode flukes (<i>Bothrigaster variolaris</i>) which infected a <a href="https://en.wikipedia.org/wiki/Snail_kite">snail kite</a> (<i>Rostrhamus sociabilis</i>), and made their way into the bird’s air sacs, causing the snail kite’s fatal end. </div><div><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQHblj7sqYgbN52ci6jNui0phlTtEbgeIc8f5lYqxPEE59QrWm-UX2wOiqnYBMo6vOcjPID8K23z8eDr7s4CQfNek15E0xBJ8jzwZbVWYoGODrPe7CK4pHgetospLNOphcf3wOOZOdSc4Ton9lsfm3pUvG7aF5cdqxE9QwwJmEqENlBzGduICzXzipnAA/s1695/Bothrigaster%20variolaris.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1080" data-original-width="1695" height="408" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQHblj7sqYgbN52ci6jNui0phlTtEbgeIc8f5lYqxPEE59QrWm-UX2wOiqnYBMo6vOcjPID8K23z8eDr7s4CQfNek15E0xBJ8jzwZbVWYoGODrPe7CK4pHgetospLNOphcf3wOOZOdSc4Ton9lsfm3pUvG7aF5cdqxE9QwwJmEqENlBzGduICzXzipnAA/w640-h408/Bothrigaster%20variolaris.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="text-align: left;">Left: Snail Kite, photo taken by <a href=" https://www.flickr.com/photos/berniedup/28412796543/">Bernard DuPont</a>, used under Creative Commons (CC BY-SA 2.0) license. <br /></span><span style="text-align: left;">Right: <i>Bothrigaster variolaris</i> fluke from Fig. 6 of the paper. </span>Centre Insert: <i>Bothrigaster variolaris</i> fluke on the pericardium of the Snail kite's heart from Fig. 1 of the paper</td></tr></tbody></table><div><br /></div><div>“Big deal,” you say, “trematodes infect air sacs in birds all the time.” And you’re right! <a href="https://bioone.org/journals/journal-of-zoo-and-wildlife-medicine/volume-54/issue-2/2021-0159/AIR-SAC-TREMATODES-CYCLOCOELIDAE-STOSSICH-1902-INFECTING-BIRDS-IN-ZOOLOGICAL/10.1638/2021-0159.short">Death from trematodes</a> <a href="https://bioone.org/journals/journal-of-zoo-and-wildlife-medicine/volume-43/issue-3/2012-0085.1/AIR-SAC-FLUKE-CIRCUMVITELLATREMA-MOMOTA-IN-A-CAPTIVE-BLUE-CROWNED/10.1638/2012-0085.1.short">infecting air sacs</a> is fairly common, but this has mostly been reported in <b>Passeriformes</b>; birds <a href="https://meridian.allenpress.com/jwd/article/57/4/906/469845/Morishitium-polonicum-as-a-Cause-of-Severe">known to be more</a> <a href=" https://www.sciencedirect.com/science/article/pii/S2213224419300525">susceptible to </a><a href="https://bioone.org/journals/journal-of-avian-medicine-and-surgery/volume-29/issue-4/2015-085/Detection-and-Management-of-Air-Sac-Trematodes-Szidatitrema-Species-in/10.1647/2015-085.short">these parasites</a>. It has even been reported in snail kites themselves, but <a href="https://meridian.allenpress.com/jwd/article/31/4/576/121940/Bothrigaster-variolaris-Trematoda-Cyclocoelidae">that was in Florida</a> rather than South America. Every continent needs its own firsts, after all. </div><div><br /></div><div>So how did this even happen? Let me explain. Snail kites, as you might have ingenuously guessed from the name, eat snails! <a href="https://en.wikipedia.org/wiki/Ampullariidae ">Apple snails</a> (<i>Pomacea</i> spp.), to be precise. Trematodes in the Cyclocoelidae family use snails as their hosts for the larval stage, meaning when those snails are eaten, little baby trematodes get to grow up into a mature adult in the body of whatever ate the snail (usually birds). So, much like eating too many candy apples can rot your teeth with cavities, the snail kite indulged in too many infected apple snails and rotted their insides. With flukes. Not cavities. And the insides weren’t rotten, just parasitised. That wasn’t that great of an analogy, actually. </div><div><br /></div><div>A wildlife rehabilitation hospital brought this male adult snail kite into their care and did their best to help him, but he passed shortly after arrival. Immediately afterwards, a necropsy was performed to poke and prod at his insides, taking tissue samples and collecting the flukes. Not the most dignified funeral rites, but it’s all in the name of science, because over <b>200 flukes</b> were counted in the bird! Thirty-five were collected for DNA analysis and were identified to be in a distinct clade within the Cyclocoelidae family. The physical characteristics of the flukes backed this up, especially the ventral sucker, which is characteristic to the genus <i>Bothrigaster</i> within that family.</div><div><br /></div><div>Researchers concluded that the bird most likely died from suffocation due to the obstruction by the parasites, as well as lesions in the respiratory tissue. They also noted a mature trematode in one of the wing bones, which is a pretty uncommon spot for a parasitic flukes to be. What an adventurer!</div><div><br /></div><div>So, these ambitious Cyclocoelidae made history by being the first reported trematodes to have caused death by air sac infection in snail kites in south America. Realistically, this may happen more than we think, and has probably been happening for quite some time, but being the first trematodes to be written about in this sense is a pretty big feat! Their mothers must be so proud. </div><div><br /></div><div>References: </div><div><a href="https://www.sciencedirect.com/science/article/pii/S2213224422000852">Díaz, E., Donoso, G., Mosquera, J. M., Ramírez-Villacís, D., González, G. T., Zapata, S. C., & Cisneros-Heredia, D. F. (2022). Death by massive air sac fluke (Trematoda: Bothriogaster variolaris) infection in a free-ranging snail kite (<i>Rostrhamus sociabilis</i>). <i>International Journal for Parasitology. Parasites and Wildlife</i> <b>19</b>: 155–160.</a></div><div><br /></div><div>This post was written by Nikita Sheelah</div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com3tag:blogger.com,1999:blog-6094038346173044955.post-37375741844737900202023-07-11T01:00:00.001-04:002023-07-11T01:00:26.820-04:00Diexanthema hakuhomaruae<div style="text-align: left;">The study in this post takes us to one of the darkest corners of the deep sea, over 7000 m below sea level in the Kuril-Kamchatka Trench, located in the northwestern Pacific. Living in this dark and oppressive environment are isopods called <i><a href="https://mapress.com/zootaxa/2015/f/z04039p224f.pdf">Eugerdella kurabyssalis</a></i>. And despite the crushing pressure, these crustaceans like it just fine, in fact they are the most abundant isopod down in those depths. But such success and abundance can also attract the attention of parasites, and this post is about a newly described parasitic copepod called <i>Diexanthema hakuhomaruae</i>.</div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEga1y3d4Ml5WOeaRSkS28ROEa8FMYirpbPU5gMZwXjsafOvBFgkFT93LXb7zgWaByRLaohYa3-kvwA6_bJYRLBaWaT5GbmI5E8IsONY5mekdxt5pmD5Kwj_HF2I6d58hsqLVlWV92ixuYILIC6igkSPT0fvmrmgaOlYFkZ4rlxD3qG50uXLQ4CfghhUM6w/s1869/Diexanthema%20hakuhomaruae.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1079" data-original-width="1869" height="370" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEga1y3d4Ml5WOeaRSkS28ROEa8FMYirpbPU5gMZwXjsafOvBFgkFT93LXb7zgWaByRLaohYa3-kvwA6_bJYRLBaWaT5GbmI5E8IsONY5mekdxt5pmD5Kwj_HF2I6d58hsqLVlWV92ixuYILIC6igkSPT0fvmrmgaOlYFkZ4rlxD3qG50uXLQ4CfghhUM6w/w640-h370/Diexanthema%20hakuhomaruae.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Left: <i>Diexanthema hakuhomaruae</i> (indicated by white arrow) attached to the leg of its <i>Eugerdella kurabyssalis</i> isopod host. Right: Close-up of <i>D. hakuhomaruae</i>, the arrow indicating the copepod's ovaries. Photos from Figure 1 of <a href="https://link.springer.com/article/10.1007/s11686-023-00676-z">the paper</a></td></tr></tbody></table><br /><div>Those who are familiar with this blog would know that parasitic copepods come in <a href="http://dailyparasite.blogspot.com/search/label/copepod">all kinds of shapes</a> that would defy most people's idea of what a crustacean is "supposed" to look like. And <i>D. hakuhomaruae</i> is no different - its tiny body is <i>ROUND</i> and if anything, it looks almost like a legless tick. And much like a tick, <i>D. hakuhomaruae</i> attaches itself stubbornly to the leg of its host.</div><div><br /></div><div><i>Diexanthema hakuhomaruae</i> belongs to the <b>Nicothoidae</b> family, a group of parasitic copepods that contains about 140 known species. They live on a variety of crustacean hosts, including <a href="https://link.springer.com/article/10.1007/s11230-015-9604-x">tanaidaceans</a>, <a href="https://link.springer.com/article/10.1007/s11230-022-10075-z">ostracods</a>, <a href="https://www.tandfonline.com/doi/abs/10.1080/00222938900770051">amphipods</a>, <a href="https://www.tandfonline.com/doi/full/10.1080/17451000902810777">cumaceans</a>, <a href="https://link.springer.com/article/10.1007/s11230-005-5483-x">mysid shrimps</a>, and <a href="https://dailyparasite.blogspot.com/2011/10/nicothoe-astaci.html">lobsters</a>. Most of them have a rotund, almost spherical body, greatly reduced or no legs at all, and a specialised mouthpart that ends in a sucker with syringe-like mandibles. And much like the ticks that they resemble, these copepods feed by stabbing their mouth syringe into their host's body and sucking up that crustacean blood (hemolymph) on tap. Some species such as <i><a href=" https://dailyparasite.blogspot.com/2014/01/choniomyzon-inflatus.html">Choniomyzon infaltus</a></i> are specialised egg parasites - their balloon-shaped bodies allow them to hide amidst broods of their hosts and feed on their eggs without being discovered.</div><div><br /></div><div><div>There are currently six other known species of <i>Diexanthema</i>, all of them are <a href="https://www.biodiversitylibrary.org/page/2292881">parasites of deep sea isopods</a>. And <i>Diexanthema </i>is not alone in its preference - there are <a href="https://www.tandfonline.com/doi/abs/10.1080/00222938300770701">other nicothoid</a> <a href="https://academic.oup.com/zoolinnean/article-abstract/79/3/297/2661645">copepods</a> that have also been found parasitising deep sea isopods. What makes <i>D. hakuhomaruae</i> special is that it is the first to be found from the <a href="https://en.wikipedia.org/wiki/Hadal_zone">Hadal Zone</a>. All other <i>Diexanthema</i> species have been reported from depths of 1300 to 3500 metres below sea level, but none of them had gone down as deep as <i>D. hakuhomaruae</i>.</div></div><div><br /></div><div>It is unknown whether <i>D. hakuhomaruae</i> feeds on the host's fluid or if it is an egg parasite, or how it even completes itself life cycle in the hadal zone - as you can imagine, discovering and describing such parasites in an environment like the deep sea is challenging enough as it is. Studying the life style and ecology of these deep sea parasites with current technology is next to impossible. Even so, this description shows that parasitism is indeed ubiquitous on this planet, and wherever you find life, you can be sure that some of them will be parasites</div><div><br /></div><div>Reference:</div><div>Kakui, K., Fukuchi, J., & Ohta, M. (2023). <i>Diexanthema hakuhomaruae</i> sp. nov.(Copepoda: Siphonostomatoida: Nicothoidae) from the Hadal Zone in the Northwestern Pacific, with an 18S Molecular Phylogeny. <i>Acta Parasitologica</i> <b>68</b>: 413-419.</div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-66630962596716464202023-06-13T20:50:00.001-04:002023-07-10T06:19:41.962-04:00Chondronema passali<div style="text-align: left;">The horned passalus beetle (<i><a href="https://en.wikipedia.org/wiki/Odontotaenius_disjunctus">Odontotaenius disjunctus</a>)</i> is an insect that is commonly found in rotting logs. These beetles do more than just eat wood, they excavate extensive tunnels within those logs where they would mate and raise a whole family of baby beetles. By doing so, they play an important ecological role in breaking down dead wood and making their nutrients accessible to other organisms in the forest such as bacteria and fungi.</div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIjqjFbCxbUbVqKaQOgF_lnQ69KsPb1zUB-U-lYG2j9alCGlvSJR7MNGrEKgji-7cKV7wSrhpvZf-1C3m70DiqxcRJXkN-kMs23e6FWZD6Acy846nfiabPLZYKFOIylwlwzzLJUi3dJ2H4oYGHR0mmBtw4t8eX_ai_Wi_IsIrgQVu8OD1IXXOorC2v/s1471/Chondronema%20passali.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1080" data-original-width="1471" height="470" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIjqjFbCxbUbVqKaQOgF_lnQ69KsPb1zUB-U-lYG2j9alCGlvSJR7MNGrEKgji-7cKV7wSrhpvZf-1C3m70DiqxcRJXkN-kMs23e6FWZD6Acy846nfiabPLZYKFOIylwlwzzLJUi3dJ2H4oYGHR0mmBtw4t8eX_ai_Wi_IsIrgQVu8OD1IXXOorC2v/w640-h470/Chondronema%20passali.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Top: A piece of dead wood with burrows made by the horned passalus beetle. Bottom left: A horned passalus beetle. Bottom right: <i>Chondronema passali </i>nematodes taken from the hemocoel of a beetle.<br />Photos from Fig 1 of <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0281149">the paper</a></td></tr></tbody></table><br /><div>Living inside these beetles is a species of nematode worm called <i>Chondronema passali</i>. These nematodes are also very common - each beetle harbours dozens to thousands of such worms, which swim freely in the beetle's hemolymph - the insect equivalent of blood. Having this many worms squirming around inside them must be affecting these beetles somehow - but how exactly?</div><div><br /></div><div>The study featured in this blog post looked at how <i>Chondronema</i> affected the beetle's "freezing" behaviour - this is a defensive response where the beetle tries to hold as still as it can so they won't get noticed by potential predators. The researchers exposed beetles to different sources of stress such as digging them out of their shelter and placing them in a brightly lit room, flipping them on their back so they can't right themselves, putting them on a tray with a vibrating phone underneath, or loudly banging the tray they're sitting on with a metal rod. All these treatments honestly sound pretty stressful even if you're <i>not</i> a beetle.</div><div><br /></div><div>The researchers observed that after being exposed to one of those distressing stimuli, female beetles tend to hold still for about twice as long as the male beetles. But this trend is flipped among beetles which have a lot of worms. For female beetles, the more worms they have, the less they seem to care about being stressed - they don't hold still for as long and seem to be in a hurry to get on with their day. In contrast, the worms seem to make male beetles more fearful, and they tend to stay still for longer after being stressed out.</div><div><br /></div><div>It is unclear why these nematodes cause their hosts to change their defensive response, and why the effects differ across the beetle's sexes. Such parasite-induced <a href=" https://www.researchgate.net/publication/325334753_The_influence_of_parasites_on_insect_behavior">behavioural changes</a> are sometimes attributed to some form of <a href=" https://journals.biologists.com/jeb/article/216/1/3/11347/Parasites-evolution-s-neurobiologists">host manipulation</a> by the parasite, altering host behaviour in such a way that would enhance the parasite's own transmission, such as making the host <a href="https://cdnsciencepub.com/doi/abs/10.1139/z96-141">more vulnerable to predators</a>. But such changes in host behaviour <a href=" https://www.sciencedirect.com/science/article/pii/S2214574518301536">isn't always</a> due to the parasite taking control, sometimes it could just be a <a href="https://www.cambridge.org/core/journals/parasitology/article/abs/behavioural-fever-in-infected-honeybees-parasitic-manipulation-or-coincidental-benefit/5E82F7094FCE1FC953301015042C12FA">side-effect</a> of the infection, and the behavioural change <a href="https://www.cambridge.org/core/journals/parasitology/article/abs/predation-of-beetles-tenebrio-molitor-infected-with-tapeworms-hymenolepis-diminuta-a-note-of-caution-for-the-manipulation-hypothesis/C33224CA162FEDE1F98920700ED7933D">doesn't always benefit</a> the parasite.</div><div><br /></div><div>Furthermore the <a href="https://bionames.org/bionames-archive/issn/0018-0130/36/190.pdf">life cycle of this nematode</a> does not involve being eaten by a predator. The beetle serves as a safe haven where young <i>Chondronema</i> grow and develop. Once they become adult worms, they leave the beetle to live amidst the tunnels excavated by their hosts. So it wouldn't be beneficial for <i>Chondronema</i> to compromise the beetle's safety, especially when they affect the male and female beetles in such different ways.</div><div><br /></div><div>Aside from the beetle's freezing behaviour, <i>Chondronema</i> can also affect their host in many other facets, including their <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0121614">fighting abilities</a>, as well as their <a href="https://www.journals.uchicago.edu/doi/abs/10.1086/689301">immune response</a>. Additionally, infected beetles also grow to be <a href="https://bioone.org/journals/The-Coleopterists-Bulletin/volume-67/issue-2/0010-065X-67.2.179/Effect-of-a-Parasitic-Nematode-Chondronema-passali-LeidyIncertae-sedis-on/10.1649/0010-065X-67.2.179.short">bigger and heavier</a>, and they <a href=" https://royalsocietypublishing.org/doi/10.1098/rsbl.2018.0842">chew through more wood</a> than their uninfected counterparts, possibly to compensate for the energetic cost of the wormy passengers inside their (larger) body. All this indicates infected beetles are physiologically compensating for the presence of the nematodes in multiple ways, so this change in their defensive behaviour might simply be a byproduct of the beetle's coping mechanisms.</div><div><br /></div><div>The impact that a parasite has on its host can manifest itself in many different ways. In the case of <i>Chondronema</i>, its effects on the host also has far-reaching implications, since these beetles play such important ecological roles. By making its host chew through more wood, this tiny worm can have a <a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2018.0842">major impact</a> on an entire forest.</div><div><br /></div><div>Reference:</div><div><a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0281149">Davis, A. K., Ladd, R. R., Smith, F., & Shattuck, A. (2023). Sex-specific effects of a parasite on stress-induced freezing behavior in a natural beetle-nematode system. <i>PloS One</i> <b>18</b>: e0281149</a>.</div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com4tag:blogger.com,1999:blog-6094038346173044955.post-40050514771567631972023-05-13T07:23:00.000-04:002023-05-13T07:23:42.490-04:00Dendrogaster nike<div style="text-align: left;">Parasitic crustaceans can <a href="http://dailyparasite.blogspot.com/2014/06/ismaila-belciki.html">evolve into</a> <a href=" http://dailyparasite.blogspot.com/2022/06/sarcotaces-izawai.html">some</a> <a href=" https://dailyparasite.blogspot.com/2020/03/pinnixion-sexdecennia.html">pretty</a> <a href="http://dailyparasite.blogspot.com/2019/06/pennella-instructa.html">funky</a> <a href="http://dailyparasite.blogspot.com/2016/10/peltogaster-sp.html">forms</a> and they have been featured multiple times on this blog. These crustaceans don't so much flaunt, but completely toss out all your expectations of what a crustacean or even an arthropod is "supposed" to look like. And among the best examples of that is <i>Dendrogaster</i>.</div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6BpnpHWRQ7FYYFFumbD3f-kyDRHISju5iFvV6hXDjW6tBhN902VduIKzcI-9ywZR0mjRnMWYTv-PUgQtF6OZ91BY0r0YUfMbk3wy5hUQY6Bby0a4CgjOLWdAGHnlL_eNfW409X0E93Kx94QXwePMEV3eJ0T1kY1guu4hg2hpjOHOm1uzuLpoIEaJm/s1475/Dendrogaster%20nike.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1063" data-original-width="1475" height="462" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6BpnpHWRQ7FYYFFumbD3f-kyDRHISju5iFvV6hXDjW6tBhN902VduIKzcI-9ywZR0mjRnMWYTv-PUgQtF6OZ91BY0r0YUfMbk3wy5hUQY6Bby0a4CgjOLWdAGHnlL_eNfW409X0E93Kx94QXwePMEV3eJ0T1kY1guu4hg2hpjOHOm1uzuLpoIEaJm/w640-h462/Dendrogaster%20nike.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Left: Female <i>Dendrogaster nike </i>side view, with attached male (bracketed in the square), Top right: Female <i>D. nike </i>frontal view, Bottom right: Male <i>D. nike</i>. Photos from Fig. 2. of <a href=" https://www.sciencedirect.com/science/article/pii/S096706372300064X">the paper</a></td></tr></tbody></table><br /><div><i>Dendrogaster</i> is a genus of crustaceans that live as internal parasites of sea stars, nestled snugly within the body cavity of its host. So much so that their body shape seems to have evolved into somewhat resembling that of its host. In contrast to other crustaceans, Instead of having hard carapaces, segments, or jointed legs, <i>Dendrogaster</i> has multiple branching lobes, like some kind of fleshy, parasitic antler. They belong to a group of crustaceans called <b><a href="https://academic.oup.com/book/38957/chapter-abstract/350630645">Ascothoracida</a></b> - a sister group to the barnacles, who themselves are no strangers to the way that evolving towards <a href=" https://dailyparasite.blogspot.com/2016/10/peltogaster-sp.html">parasitism can warp their body</a>.</div><div><br /></div><div><i>Dendrogaster</i> rivals those parasitic barnacles in the "WTF Evolution?" department, and despite how bizarre they may look to us, they are not some rare oddity lurking in an obscure corner of the world. There are 35 known species of <i>Dendrogaster</i> and they have been found parasitising eighteen different families of sea stars all over the world, ranging from those dwelling in the shallows, to those inhabiting the deep sea over 2500 m below sea level. It seems that wherever sea stars went, <i>Dendrogaster</i> followed.</div><div><br /></div><div>The paper featured in this blog post adds another species to this roster of evolutionary weirdos. This newly described species was found from sea stars living 1970 m below sea level, collected during a biodiversity survey at the An'ei Seamount, an offshore marine protected area off the eastern coast of Japan. The host was <i><a href="https://www.jstage.jst.go.jp/article/specdiv/27/2/27_SD22-08/_article/-char/ja/">Asthenactis agni</a></i> - a sea star which itself was newly discovered and described just late last year. This parasitic crustacean has multiple, wing-like branches protruding from its body, and it is this appearance which inspired its scientific name, <i>Dendrogaster nike</i>, named after <a href=" https://en.wikipedia.org/wiki/Nike_(mythology)">Nike</a>, the Greek winged goddess of victory.</div><div><br /></div><div>But that's only how the female of the species looks like. The male is less than a quarter the size of its partner, and unlike the female <i>Dendrogaster</i> with its multiple protruding branches, the male is comparatively unremarkable, with a simple ovoid-shaped body and a pair of long thin testes dangling from it. It is usually found attached to its much larger and more flamboyant partner, floating inside the body cavity of a sea star.</div><div><br /></div><div><i>Dendrogaster nike</i> is just one of many new species of <i>Dendrogaster</i> that have been described over the last few years. In 2020, there were <a href=" https://www.jstage.jst.go.jp/article/specdiv/25/1/25_250108/_article/-char/ja/">three other species of <i>Dendrogaster</i></a> which had been discovered from sea stars collected from the depths of the <a href="https://en.wikipedia.org/wiki/Bathypelagic_zone">bathyal zone</a>. It seems that sea stars from the deep sea are particularly favoured by this parasitic crustacean, and there are probably many other species of <i>Dendrogaster</i> yet to be discovered which are lurking in the abyss.</div><div><br /></div><div>When scientists compared the DNA sequences of different <i>Dendrogaster</i> species, they found that the genus seems to be divided into two main sub-groups - those who stuck to the shallows, and those who ended up partying in the deep. While the evolutionary pathways of many parasites somewhat parallel that of their hosts, for <i>Dendrogaster</i>, it followed the hosts' habitats instead. This may provide some insight into the evolutionary origin of this bizarre, but widely found group of parasitic crustaceans.</div><div><br /></div><div>When life hands you a sea star, sometimes it comes with a free <i>Dendrogaster</i>.</div><div><br /></div><div>Reference:</div><div>Jimi, N., Kobayashi, I., Moritaki, T., Woo, S. P., Tsuchida, S., & Fujiwara, Y. (2023). Insights into the diversification of deep-sea endoparasites: Phylogenetic relationships within <i>Dendrogaster</i> (Crustacea: Ascothoracida) and a new species description from a western Pacific seamount. <i>Deep Sea Research Part I: Oceanographic Research Papers</i> <b>196</b>: 104025.</div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-35422165404906812432023-04-13T19:43:00.001-04:002023-04-14T02:45:08.582-04:00Rickia wasmannii <div style="text-align: left;"><i>Rickia wasmannii</i> is a fungus that lives on ants, and when it comes to ants and fungi most people usually think of <i><a href=" https://dailyparasite.blogspot.com/2017/01/ophiocordyceps-pseudolloydii.html">Ophiocordyceps</a></i>, i.e. the zombie ant fungus - which was the inspiration for <i>The Last of Us</i> series of video games and TV series. But <i>R. wasmannii</i> is not a killer - instead of zombifying its host and digesting the corpse, this fungus seems to reduce animosity and aggression between ants. First of all, let's take a look at what <i>R. wasmannii</i> actually does on ants. </div><div style="text-align: left;"><br /></div><div style="text-align: left;"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvPXym8BrGcT9k7xn8edstUgyq6mjk5JVZpAmWMnoCadPJCLYvLm3uDnJq4Ok5f-B5KVA46qyr8zXtxrsmhxjRaidRZ3xLy2HZp7gV7R2drxgDpRa_n57H6OAzPshXz8TbKbFryue-oKZ3AYonMeHSyWMezj0L2ZFramjh_5dCagpEuYP83l4LVsgi/s1297/Rickia%20wasmannii.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1075" data-original-width="1297" height="530" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvPXym8BrGcT9k7xn8edstUgyq6mjk5JVZpAmWMnoCadPJCLYvLm3uDnJq4Ok5f-B5KVA46qyr8zXtxrsmhxjRaidRZ3xLy2HZp7gV7R2drxgDpRa_n57H6OAzPshXz8TbKbFryue-oKZ3AYonMeHSyWMezj0L2ZFramjh_5dCagpEuYP83l4LVsgi/w640-h530/Rickia%20wasmannii.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Left: Illustration of a <i>Rickia wasmannii</i> thallus, Right top: Uninfected ant, Right bottom: ant infected with <i>R. wasmannii</i><br />Pictures from Figure 1 of <a href=" https://www.nature.com/articles/s41598-021-02800-3">this paper</a></td></tr></tbody></table><i><br /></i></div><div style="text-align: left;"><i>Rickia wasmannii</i> belongs to a group of fungi called <b><a href=" https://en.wikipedia.org/wiki/Laboulbeniales">Laboulbeniales</a></b>, also known more colloquially as "labouls". These fungi have little holdfasts called haustoria that allows them to cling to the ant's cuticle. They are ectoparasites of insects that attach to their host's external surface and suck their hemolymph (insect's equivalent of blood). So in a way they are rather like ticks or lice (and yes, there are labouls that live on <a href=" http://dailyparasite.blogspot.com/2017/04/arthrorhynchus-nycteribiae.html">ectoparasitic insects</a>, which one might consider as a bit of poetic justice).</div><div class="Ar Au Ao" id=":1cl"><div aria-controls=":1fa" aria-label="Message Body" aria-multiline="true" aria-owns=":1fa" class="Am Al editable LW-avf tS-tW tS-tY" g_editable="true" hidefocus="true" id=":1ch" role="textbox" spellcheck="false" style="direction: ltr; min-height: 245px;" tabindex="1"><br />But this fungus seems to do more than just suck the ant's blood, as it causes the infected ants and other ants around them to behave differently. <i>Rickia wasmannii</i> changes the host ant's cuticular hydrocarbon or CHC profile. CHC is essentially an ant's ID profile - they use it to recognise nestmates, tell each other apart, and be alerted to strangers from other nests. But <i>R. wasmannii</i> messes with that, scrambling the infected ants' CHC profile, and making them "smell" differently to uninfected ants.<br /><br />Scientists wanted to find out how the presence of this fungus affects the way ants interact with each other. The challenge with studying ant behaviour is that when you put two ants together, it is difficult to tell apart whether the ant you are observing is responding to the other ant's chemical profile, or if it is responding to the way the other ant is reacting to them. The only way to get a clear observation is to present the ant with something that it would recognise as a fellow ant, but would not muddle the outcome by reacting to the ant that you are trying to observed<br /><br />The solution turns out to be freeze-killed ants. Ants that are killed in this manner retain their CHC profile, so other ants would treat them just as another live ant, but obviously a dead ant wouldn't react to a live ant's presence and confound the outcome. In addition to those freeze-killed test subjects, scientists also made ant "dummies" which are essentially blank slates in ant forms that they can imbue with whatever chemical signature they were testing. These "dummies" were made by washing ant corpses in hexane to remove their chemical signature. To ants, these specially treated ant corpses are like faceless mannequin, with no identity - until the scientist imbues them with one, by anointing them with a droplet of cuticular extract from another ant.<br /><br />When ants were presented with dummies that were smeared with the cuticular extract of ants from a different nest, the ants started biting, dragging, or stinging the dummies, much like how they would respond to a live ant from another nest. But when they were presented with either the corpse of a <i>Rickia</i>-infected ant, or dummies that "smell" like a <i>Rickia</i>-infected ant, they were more relaxed and less likely to get aggro. Furthermore, it's not just that the fungus made other ants act differently, the infected ant itself also starts behaving differently. Infected ants are generally less likely to pick a fight with another ant, but especially when facing other infected ants.<br /><br />As mentioned previously, <i>R. wasmannii</i> seems to change the ant's CHC profile, but one would think scrambling the host ant's profile would make other ants react <i>more</i> aggressively towards them since ants usually have a "stranger danger" response to ants that "smell" different to their nestmates. But the way that <i>R. wasmannii</i> changes how an ant "smell" seems to have a calming effect, and this comes down to a molecule called <b>n-C23</b> which is present in higher concentration on the cuticle of all infected ants. When the scientist presented ants with dummies that have been smeared with n-C23 and nothing else, almost all hints of aggressive behaviour ceased.<br /><br />So by increasing n-C23 concentration in its host's cuticle, <i>R. wasmannii</i> has unlocked a life hack that allows it to not just access all areas in an ant colony, but to spread to other nests as well. In the scientists' study population, about half the colonies they studied had the fungus present, and in some nests, <a href="https://www.sciencedirect.com/science/article/pii/S0022201116300246">all the ants were infected</a> with <i>R. wasmannii</i>. A testament to the fungus' successful manipulation of ant behaviour.<br /><br />Furthermore the fungus' presence also affects another, very different parasite which also lives with ants - the caterpillar of <a href="https://en.wikipedia.org/wiki/Phengaris">blue butterflies</a>. These caterpillars are social parasites that convince worker ants into adopting them into their nest. Once they are settled in, they start demanding food from the worker ants and even feed on the ant's developing broods. But the caterpillars don't seem to survive as long in nests which are already hosting <i>R. wasmannii</i>, and in the field, these two parasites co-occur less commonly than expected based on their respective prevalence, which indicates the caterpillar and the fungus are <a href=" https://www.nature.com/articles/s41598-021-02800-3">in competition over ant real estate</a>.<br /><br />By messing with their identity and making them more chilled out, <i>R. wasmannii</i> can turn an ant colony into a fungus party. But the consequences of that ripple out to other ant colonies too, along with the organisms that regularly take up residency in the homes of ants.<br /><br />Reference:<br /><a href="https://www.nature.com/articles/s42003-023-04541-7">Csata, E., Casacci, L. P., Ruther, J., Bernadou, A., Heinze, J., & Markó, B. (2023). Non-lethal fungal infection could reduce aggression towards strangers in ants. <i>Communications Biology</i>, <b>6</b>: 183.</a><br /></div></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-87059059670928739302023-03-17T00:56:00.000-04:002023-03-17T00:56:35.562-04:00Inodosporus fujiokai<div style="text-align: left;">A few years ago, rainbow trout at a trout farm in the Shiga prefecture, Japan, were being struck down by a mysterious illness. The flesh of the dead fish were speckled with red dots and white cysts. It turns out the disease was caused by a type of previously <a href="https://www.jstage.jst.go.jp/article/jsfp/56/3/56_130/_article/-char/ja/">unknown microsporidian parasite</a>. Microsporidians have been reported from other farmed fish in Japan, where they are locally called "beko disease". It was suspected that the trout might be getting infected from their food, and during feeding trials it was found that trout fed with fresh or chilled prawns developed the disease, while those fed frozen prawns stayed healthy. This shows that prawns were somehow involved in the life cycle of this parasite.</div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhK8O8YtS9TrjUkj999DYRU2rOgZY8n8FRHzTjL8AN_xgLN-fqzBLPAiDGdNHu2hx44z0Rry0_P7eHtlgdFzYJ27AKlfdieVBK4CQUkh8G3OmnqutvUiftELRtsdCWz4KrmJaWy-RJd16Ydaeg-TSLjiOfHb2ew5rC0mzuoo3MmjmBn0gI3MYI8KbFG/s1663/Inodosporus%20fujiokai.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1073" data-original-width="1663" height="412" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhK8O8YtS9TrjUkj999DYRU2rOgZY8n8FRHzTjL8AN_xgLN-fqzBLPAiDGdNHu2hx44z0Rry0_P7eHtlgdFzYJ27AKlfdieVBK4CQUkh8G3OmnqutvUiftELRtsdCWz4KrmJaWy-RJd16Ydaeg-TSLjiOfHb2ew5rC0mzuoo3MmjmBn0gI3MYI8KbFG/w640-h412/Inodosporus%20fujiokai.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Left: Prawn infected with <i>Indosporus fujiokai </i>(indicated by red arrow), Centre: Electron microscopy of spores from muscles of an infected prawn (top), and a spore from the muscles of an infected trout (bottom). Right: An infected trout showing signs of hypoxia associated with infection by <i>I. fujiokai </i>(top), muscles of infected trout with red specks and white cysts of the parasite as indicated by arrows (bottom).<br />Photos of prawns + spores from Fig. 1, 7, and 9 of <a href="https://www.cambridge.org/core/journals/parasitology/article/molecular-and-morphological-description-of-a-novel-microsporidian-inodosporus-fujiokai-n-sp-infecting-both-salmonid-fish-and-freshwater-prawns/D5EAA2CE928BC8879EA679FC552F2521">the paper,</a> Photos of infected trout + their flesh from Fig. 3 and 6 of <a href="https://www.jstage.jst.go.jp/article/jsfp/56/3/56_130/_article/-char/ja/">this paper</a></td></tr></tbody></table><br /><div><a href="https://en.wikipedia.org/wiki/Microsporidia">Microsporidians</a> are single-celled parasites which are related to fungi. There are 1500 known species, though the actual number of microsporidians out there is likely to be much higher. For most of them, relatively little is known aside from how they look like and what they infect. About half of all known microsporidians are <a href=" https://www.sciencedirect.com/science/article/pii/S1471492213001414">parasites of aquatic animals</a> (and <a href="http://dailyparasite.blogspot.com/2021/09/unikaryon-panopei.html"><i>their </i>parasites</a>), and <a href=" https://www.sciencedirect.com/science/article/abs/pii/S1286457901013946">their life cycles</a> can vary considerably between different species. Despite their importance as parasites of fish and crustaceans in aquaculture, the life cycles of many microsporidians are unknown. </div><div><br /></div><div>In the study featured in this blog post, researchers set out to find samples of the Shiga trout farm parasite out in the wild - and they found it amidst some prawns from <a href="https://en.wikipedia.org/wiki/Lake_Biwa">Lake Biwa</a>. Microsporidian-infected prawns are easy to spot because in contrast to healthy prawns which are translucent, infected prawns become opaque white as the parasite proliferates in their muscles. But surprisingly, despite the numerous spores filling up their flesh, infected prawns seemed rather healthy and were able to live for several weeks in the lab. Some of them even managed to produce eggs despite being parasitised! This is in stark contrast to the effect that this parasite has on its trout hosts.</div><div><br /></div><div>The researchers named this microsporidian <i><b>Indosporus fujiokai</b></i> - after a parasitologist who, back in 1982, suggested the involvement of prawns in the transmission of microsporidian parasites. But that is not the entire story, because those prawns were harbouring a lot more than just <i>I. fujiokai</i>. The researchers actually found <b>FOUR</b> different types of microsporidians in those prawns, including the one that they eventually named <i>Indosporus fujiokai</i>. These microsporidians all differ in their spore sizes and shapes, and all of them were entirely new to science. Three of the microsporidians, including <i>I. fujiokai</i>, belong to a group called "<b>Marinosporidia</b>'' which are usually found infecting fish and aquatic invertebrates - this was to be expected since they were examining prawns. However, one of the microsporidians was more unusual, as it hails from an entirely different part of the microsporidian tree called "<b>Terresporidia</b>", which is composed of species that <a href="https://en.wikipedia.org/wiki/Nosema_(microsporidian)">usually infect </a><a href="https://en.wikipedia.org/wiki/Vairimorpha">insects</a>.</div><div><br /></div><div>The results of this study suggests that prawns and other crustaceans could be harbouring a rich array of microsporidian parasites that are currently unknown to science, and there might be many more of them out there which are infecting fish by the way of crustacean hosts. While the researchers in this study were able to resolve the life cycle for <i>I. fujiokai</i>, mysteries continue to surround the life cycles of the three other microsporidians that they found - what hosts they might infect in the next stage of their respective life cycles are anyone's guess at this point.</div><div><br /></div><div>As is often the case with parasites, just as you manage to answer one question, three (or more) others pop up in the process. So if life gives you a raw prawn, you should examine it for parasites.</div><div><br /></div><div>Reference:</div><div><a href="https://www.cambridge.org/core/journals/parasitology/article/molecular-and-morphological-description-of-a-novel-microsporidian-inodosporus-fujiokai-n-sp-infecting-both-salmonid-fish-and-freshwater-prawns/D5EAA2CE928BC8879EA679FC552F2521">Yanagida, T., Asai, N., Yamamoto, M., Sugahara, K., Fujiwara, T., Shirakashi, S., & Yokoyama, H. (2023). Molecular and morphological description of a novel microsporidian <i>Inodosporus fujiokai</i> n. sp. infecting both salmonid fish and freshwater prawns. <i>Parasitology</i> <b>150</b>: 1-14.</a></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-16294669800216780702023-02-13T19:03:00.004-05:002023-02-14T23:51:02.473-05:00Parvatrema sp.<div style="text-align: left;">Pearls may look beautiful to us, but for some parasites, they represent a slow and claustrophobic death. Pearls are secreted by the soft and fleshy <a href="https://en.wikipedia.org/wiki/Mantle_(mollusc)">mantle</a>, the part of a mollusc's body that also produces the shell. Indeed, pearls and shells are made from the same material - calcium carbonate. For the shellfish that produce them, pearls are battle scars of their fight against parasites.</div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUccvONv-74TJPNTDso_NIKgYCztOPSnw6-SixOsXwQCu-kOISKZabtvaaU0UA6-WO8hwEKAcoewIlRj_XlXm4cQc_HG-hlxqNKau3UWX5wsZw0SvTHfu3kGwT02YndBtKmuhny3VLLhbwW6EJO2TTEvA4xcLUHk2ZLopO-2uvhYijihX7uy5ALk6P/s1893/Parvatrema.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1601" data-original-width="1893" height="542" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUccvONv-74TJPNTDso_NIKgYCztOPSnw6-SixOsXwQCu-kOISKZabtvaaU0UA6-WO8hwEKAcoewIlRj_XlXm4cQc_HG-hlxqNKau3UWX5wsZw0SvTHfu3kGwT02YndBtKmuhny3VLLhbwW6EJO2TTEvA4xcLUHk2ZLopO-2uvhYijihX7uy5ALk6P/w640-h542/Parvatrema.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Top left: Mussel infected with <i>Parvatrema</i>, Top right: Pearls from a mussel Bottom left: <i>Parvatrema </i>metacercaria stage from a mussel, Bottom right: Cross-section of a pearl showing three flukes trapped within. <br />Top row of photos from Fig 1 of <a href=" https://link.springer.com/article/10.1007/s41208-022-00415-7">this paper</a>. Bottom row of photos from Fig. 2 of <a href="https://www.sciencedirect.com/science/article/abs/pii/S0022201122001409">the paper</a>.</td></tr></tbody></table><br /><div style="text-align: left;">Bivalves are host to a <a href="https://www.sciencedirect.com/science/article/pii/S0399178400001389">wide range</a> <a href="https://bioone.org/journals/Journal-of-Parasitology/volume-92/issue-2/GE-3510.1/DIGENEAN-LARVAE-PARASITIZING-span-classgenus-speciesCERASTODERMA-EDULE-span-BIVALVIA-AND/10.1645/GE-3510.1.full">of different</a> <a href="https://www.cambridge.org/core/journals/parasitology/article/abs/interactions-between-parasites-of-the-cockle-austrovenus-stutchburyi-hitchhikers-residentcleaners-and-habitatfacilitators/964CF0D53E29324EE2C85E6531938FDA">parasites</a> that use them as a home, a site of propagation, or even as a convenient vehicle to their next host. One of the most common types of parasites that infect bivalves are <a href="http://dailyparasite.blogspot.com/search/label/trematode">trematode</a> flukes. Some species embed themselves stubbornly in the mollsuc's tissue, others <a href="https://www.cambridge.org/core/journals/journal-of-helminthology/article/abs/equal-partnership-two-trematode-species-not-one-manipulate-the-burrowing-behaviour-of-the-new-zealand-cockle-austrovenus-stutchburyi/118A610D1585458267A09D86456B5B7A">impair their ability to use parts of their body</a>, and there are even some that end up <a href="https://www.int-res.com/abstracts/dao/v59/n2/p151-158/">castrating their shellfish host</a>. Sometimes, these seemingly passive molluscs put up a fight against these tiny intruders, especially when they get into the mantle fold. And they do so by secreting calcium carbonate around the invading parasite, smothering these flukes alive - and the result of that gruesome interaction is a pearl.</div><div><br /></div><div>The study being featured in this post looked at the frequency of pearls and parasites in mussels on the northwestern Adriatic coast. The flukes that are most commonly associated with pearls there are those from the <b>Gymnophallidae</b> family, and this study focus on one particular genus - <i>Parvatrema</i>. These flukes use mussels as their intermediate host, where the larvae temporarily reside and develop until they are eaten by shorebirds - this parasite's final host.</div><div><br /></div><div>Out of the 158 mussels that the researchers examined, about two-thirds of them were infected, and most of the mussels had a mix of both live flukes and pearls.Their parasite load varied quite a lot, from some mussels with a few flukes, to one with over 3700 flukes. But on average, each mussel harboured about 200 flukes. The flukes were scattered throughout the mussel's body, but most were concentrated near the gonads, and some were found at the base of the gills. A few were squeezed in between the mantle and the shell - and it is those that are at the most risk of being turned into pearls. </div><div><br /></div><div>Speaking of which, about half the mussels that the researchers examined had pearls of some sort in them. But there were far fewer pearls than there were flukes. Each mussel had 35 pearls on average, but they were nowhere near the size of pearls most people associate with jewellery. These pearls were about the same size as fine sand grains, but they were pearls nevertheless - complete with entombed fluke(s) in each of them.</div><div><br /></div><div>The high prevalence of <i>Parvatrema</i> in mussels from this area means that it could be risky to set up mussel farms there, at least near the coast where the parasite's bird hosts like to hang out. No one wants to buy mussels riddled with parasites, and while pearls are considered as valuable, the type of pearls found in these mussels only decrease their market value. That is one of the reasons why some mussel farming operation are <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/raq.12549">located offshore</a> where they won't be exposed to <i>Parvatrema</i> and other parasitic flukes. </div><div><br /></div><div>Based on the results of the study, pearl formation seems a bit hit-or-miss as a defensive mechanism. The majority of flukes get away with living rent-free in the mussels without setting off the pearly deathtraps, and it's not entirely clear why some of them trigger pearl formation, while most flukes are left alone. Despite this, some recent studies indicate that bivalves are not the only molluscs that can entomb their parasites that way. Some land snails are also capable of sealing away various parasites such as <a href="https://www.parasite-journal.org/articles/parasite/full_html/2023/01/parasite220116/parasite220116.html">flukes</a> and <a href=" https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5500577/">roundworms</a> into their shell. </div><div><br /></div><div>So it seems the molluscs have evolved a general two-in-one defensive package that can potentially protect them against both predators and parasites. While neither shell nor pearls offer guaranteed protection against predators and parasites respectively, it's still better than having nothing at all.</div><div><br /></div><div>Reference:</div><div>Marchiori, E., Quaglio, F., Franzo, G., Brocca, G., Aleksi, S., Cerchier, P., Cassini, R. & Marcer, F. (2023). Pearl formation associated with gymnophallid metacercariae in <i>Mytilus galloprovincialis</i> from the Northwestern Adriatic coast: Preliminary observations. <i>Journal of Invertebrate Pathology</i> <b>196</b>: 107854.</div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-87603007245585355142023-01-15T19:32:00.000-05:002023-01-15T19:32:14.464-05:00Leucochloridium passeri<div style="text-align: left;"><i>Leucochloridium paradoxum </i>is one of those parasites which is immediately recognisable on sight. Commonly known as the "zombie snail parasite", its habit of turning the eyestalks of snails into pulsating candy canes has also earned it the name "green-banded broodsac", and it has appeared in various forms of media, including the opening of the <a href="https://www.youtube.com/watch?v=dFlDRhvM4L0"><i>Chainsaw Man</i> anime</a>. But far from just being a bizarre one-of-a-kind oddity, <i>L. paradoxum</i> is just <a href=" https://www.sciencedirect.com/science/article/pii/S1383576919301473">one out of ten known species</a> in the <i>Leucochloridium</i> genus which infect <a href="https://en.wikipedia.org/wiki/Succineidae">amber snails</a> and produce these "broodsacs" structures. And these colourful, pulsating sacs are the key for distinguishing <a href="https://dailyparasite.blogspot.com/2016/12/leucochloridium-paradoxum-revisited.html">different species of <i>Leucochloridium</i></a>.</div><div><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjv_txWGm31ZYwFUmcHXoe5I-cFKOsOW01ermXHqvgISbIKO7N2bVF-Vm496cWFJC96m4wQA95AU7pWRRFGh624ee0y2rEXtmqBjbntygi6Qmpl_fK2zky8ggUje-H8QCnLuDIs0y5X7rvlDZiL-F8KS7v23VHLO1RioRT_tsAcltgEH26KHCqx5n_X/s2090/Leucochloridium%20passeri.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1522" data-original-width="2090" height="466" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjv_txWGm31ZYwFUmcHXoe5I-cFKOsOW01ermXHqvgISbIKO7N2bVF-Vm496cWFJC96m4wQA95AU7pWRRFGh624ee0y2rEXtmqBjbntygi6Qmpl_fK2zky8ggUje-H8QCnLuDIs0y5X7rvlDZiL-F8KS7v23VHLO1RioRT_tsAcltgEH26KHCqx5n_X/w640-h466/Leucochloridium%20passeri.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Left: Snail infected with <i>Leucochloridium passeri </i>collected from Hemei Township (Changhua County) by Jui-An Lin, photo from Fig. 1 of the paper. Top right: Labelled <i>L. passeri </i>broodsac from Fig. 1 of the paper. Bottom right: A trio of <i>L. passeri </i>broodsacs with metacercariae removed from an infected snail, from Supplementary video 3 of <a href="https://www.sciencedirect.com/science/article/pii/S1383576922001088">the paper</a></td></tr></tbody></table><div><br /></div><div>The adult stage of <i>Leucochloridium</i> are found in birds where they dwell in the cloaca or a special organ called <a href=" https://en.wikipedia.org/wiki/Bursa_of_Fabricius">Bursa of Fabricius</a>. While parasite identification is usually based upon the various anatomical features of the adult parasite, in the case of <i>Leucochloridium</i>, the adult flukes of different species all look rather similar to each other. In contrast, the broodsac stages come in a wide variety of colours and patterns that are extremely noticeable and unique to each species. So short of comparing their DNA sequences, the colours and stripes of the larval broodsacs are the most reliable way to tell apart the different species.</div><div><br /></div><div>This blog post features a study on <i>Leucochloridium passeri</i>, a species that was first described as adult flukes from Eurasian tree sparrows in Guangdong, and has subsequently been found across the <a href=" https://en.wikipedia.org/wiki/Indomalayan_realm">Indomalayan realm</a>. It is one of five different <i>Leucochloridium</i> species found in Taiwan, but it is the only one for which their broodsac stage has been documented. While not as well known as <i>L. paradoxum</i>, its broodsacs nevertheless present an attention-grabbing sight. You might recognise it from <a href="https://www.facebook.com/groups/283177105146997/permalink/1618117384986289/">this video</a>, which has gone viral and been posted all over the internet, usually without credit or attribution of the original source.</div><div><br /></div><div>It can be easily distinguished from <i>L. paradoxum </i>and other <i>Leucochloridium</i> species by a distinctive wide band of red-brown patches or longitudinal stripes in the mid-section of each mature broodsac. Many people who have some familiarity with this parasite would know about the pulsating sacs forcing their way into the snail's eye tentacles, but what they might not know is that those are only part of the entire parasite mass residing within the snails.</div><div><br /></div><div>Those pulsating "broodsacs" are actually the parasite's asexual larvae. In addition to the very flamboyant mature broodsacs, there are also translucent immature broodsacs which are tucked away deeper in the snail's body. Digenean flukes have an asexual stage in their life cycle, and in most flukes they produce hundreds to thousands of sausage-shaped asexual larvae in the snail's body. Those wriggly sausages would then give birth to free-swimming larvae called cercariae that are release into the environment where they infect the next host in the life cycle. In the case of <i>Leucochloridium</i>, the cercariae stay in those wriggly sausages and develop into round, jelly-coated cysts within the snail. Each mature broodsac can contain up to two hundred cysts, so when a bird swallows one of these colourful wriggling sausages, they are inviting hundreds of flukes to take up residency in their cloaca.</div><div><br /></div><div>The <i>L. passeri</i> broodsacs described in this study were found in <a href="https://en.wikipedia.org/wiki/Yilan_County,_Taiwan">Yilan County</a> in Taiwan, and they look very similar to some <i>Leucochloridium</i> broodsacs which have been <a href="https://www.sciencedirect.com/science/article/pii/S1383576919301473">found in Okinawa</a>, Japan. They both have the distinctive wide band of red-brown stripes and splotches, and when researchers compared their DNA sequences, they found that they both belong to the same species - <i>Leucochloridium passeri</i>.</div><div><br /></div><div>Relatively little is known about the birds that can serve as the final hosts for <i>L. passeri</i>, but researchers have noticed that the distribution of various <i>Leucochloridium</i> species in different zoogeographical regions seems to be related to the <a href="https://www.sciencedirect.com/science/article/pii/S1383576919301473">distribution of birds and amber snails</a> which are native to those particular regions. Since some of those birds are migratory, this provides <i>Leucochloridium</i> with the means to cross oceans while seated snugly in the butt of their feathery host, ready to settle down wherever there are amber snails to infect. </div><div><br /></div><div>Reference:</div><div>Chiu, M. C., Lin, Z. H., Hsu, P. W., & Chen, H. W. (2022). Molecular identification of the broodsacs from <i>Leucochloridium passeri</i> (Digenea: Leucochloridiidae) with a review of <i>Leucochloridium</i> species records in Taiwan. <i>Parasitology International</i> 102644.</div><div><br /></div><div><i>P.S. </i>Leucochloridium<i> is a very distinctive parasite and has been subjected to numerous artistic depictions, here's my own artistic depiction of </i>Leucochloridium<i> in the form of a <b><a href=" https://www.deviantart.com/the-episiarch/art/Luci-the-Leucochloridium-Monster-Girl-853408037">Parasite Monster Girl</a></b>.</i></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-73923830391853749522022-12-14T23:26:00.001-05:002022-12-14T23:48:48.155-05:00Stenurus globicephalae<div style="text-align: left;">Whales are big animals, even the "smaller" cetaceans such as dolphins and pilot whales are large animals in the range of body sizes across the animal kingdom. The thing about big animals is that they provide a lot of room for parasites. The myriad array of spacious organs found in an animal like a whale provide ample opportunities for parasites to become very specialised not just on a particular species of host, but on a very specific niche within the host's anatomy. Unsurprisingly, there are a <a href=" https://www.otago.ac.nz/parasitegroup/PDF%20papers/Lehnertetal2019-JoH.pdf">wide range of parasites</a> that make their home inside whales. With so many different species inhabiting different parts of the whale anatomy, it is perhaps not surprising that there are worms that specialise in living within the voluminous lungs and sinuses of whales. One of them is a genus named <i>Stenurus</i>.</div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjCGi7xSDkJ4X8w-d2f_p-LlENitb4mzGvkW0fG0TbwvG3lxKOAO8V7J2RkkkOwAgNRlYCuqTtDeGjH5OxKKKE0x2nui7yIViYHvcfmENWxP_RxywQAGX2IHa50pGu5m6pYFEGmtURVAunCtyw2LYxbcUZHOk4I3rBhd2-17yl5ktJv42eF4kLO3o8/s1184/Stenurus%20globicephalae.jpg" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="920" data-original-width="1184" height="498" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjCGi7xSDkJ4X8w-d2f_p-LlENitb4mzGvkW0fG0TbwvG3lxKOAO8V7J2RkkkOwAgNRlYCuqTtDeGjH5OxKKKE0x2nui7yIViYHvcfmENWxP_RxywQAGX2IHa50pGu5m6pYFEGmtURVAunCtyw2LYxbcUZHOk4I3rBhd2-17yl5ktJv42eF4kLO3o8/w640-h498/Stenurus%20globicephalae.jpg" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Numerous <i>Stenurus</i> worms in the pterygoid sinuses of a short-finned pilot whale (<i>Globicephala macrorhynchus</i>). <br />Photo from Fig. 1 of the paper. </td></tr></tbody></table><br /><div style="text-align: left;">There are nine known species of <i>Stenurus</i>, all of them live in the respiratory system and sinuses of whales. Each of those worms differ in the particular cetacean species that they infect, as well as the part of the host's respiratory system they inhabit. The study being covered in today's blog post were based on samples collected from fourteen toothed whales that had been stranded along the Galicia coast between 2009 and 2019. There were a mix of six different whale species in total, and considering the population of parasites that each whale could support, it provided researchers with plenty of material to work with. Unlike most other parasitological studies where the dissection takes place in the controlled environment of a laboratory, you can't exactly bring a dead whale back to your lab. So instead, the parasites were collected via on-site necropsies.</div><div><br /></div><div>The researchers found many different species of lung parasites from the different whales, including three species of <i>Stenurus</i>. But out of them, the most abundant was <i>Stenurus globicephalae</i>, which was found in three host species including <a href=" https://en.wikipedia.org/wiki/Risso%27s_dolphin">Risso's Dolphin</a>, <a href=" https://en.wikipedia.org/wiki/Short-finned_pilot_whale">Short-finned pilot whales</a>, and <a href="https://en.wikipedia.org/wiki/Long-finned_pilot_whale">Long-finned pilot whales</a>. Each whale harboured between 18 to over 1700 of those worms, which were mostly found in the pterygoid sinus, located deep within the nasal passage near the back of the whale's throat. Previous studies have also recorded <i>S. globicephalae</i> dwelling in the lungs as well as other canals and cavities in a whale's head including the middle ear cavities and cranial sinuses. These worms seem to like dwelling in soft, moist tubes.</div><div><br /></div><div><i>Stenurus globicephalae</i> was found to be particularly prolific in short-finned pilot whales, which indicates that while it is capable of infecting other whale species, the short-finned pilot whale just so happens to be a particularly good "fit" for it. Each <i>Stenurus</i> species differ in their host preferences, and it seems to be related to how they get transmitted to the whale in the first place. Like with many <a href="https://dailyparasite.blogspot.com/2021/05/anisakis-physeteris.html">other nematodes that infect whales</a>, they do so by hiding in their host's food.</div><div><br /></div><div>The researchers noticed a certain pattern of association between different species of <i>Stenurus</i> with the diet of the whale species they infect. For example <i>S. globicephalae</i> was associated with species that mostly ate squid, whereas those that ate fish or have a mixed diet tend to be infected with <i>S. ovatus</i> and <i>S. minor</i>. So it is a case of "you are infected by what you eat".</div><div><br /></div><div><i>Stenurus</i> was not alone in its preference for whale respiratory structures. In some of the whales, the researchers found <i>Stenurus</i> cohabiting those airy passages with other parasites. One of those co-inhabitants was <i><a href=" https://dailyparasite.blogspot.com/2010/04/april-24-halocercus-delphini.html">Halocercus</a></i> - a different genus of whale lungworm which anchor themselves in place by plunging their head firmly into the host tissue. Another co-inhabitant was <i><a href="https://dailyparasite.blogspot.com/2010/04/april-20-nasitrema-globicephalae.html">Nasitrema</a></i> - a fluke that lives in the air sinuses of small whales and has a nasty tendency to wander into the host's brain.</div><div><br /></div><div>While having worms in your sinuses sounds uncomfortable, <i>Stenurus</i> lead a relatively peaceful existence within their wet, cosy homes, and their presence causes surprisingly little to no inflammatory responses. Or at least they do once they settle down as adult worms, because the larval worms can potentially cause focal pneumonia, while the adult worms have a more relaxed relationship with their surroundings. It is as if the whales progressively grow used to their presence, or the worms have grown to tame the fiery response of their host's immune system.</div><div><br /></div><div>Reference:</div><div><a href="https://www.sciencedirect.com/science/article/pii/S2213224422000864">Saldaña, A., López, C. M., López, A., Covelo, P., Remesar, S., Martínez-Calabuig, N.,García-Dios, D., Díaz, P., Morrondo, P., Díez-Baños, P., & Panadero, R. (2022). Specificity of <i>Stenurus</i> (Metastrongyloidea: Pseudaliidae) infections in odontocetes stranded along the north-west Spanish coast. <i>International Journal for Parasitology: Parasites and Wildlife </i><b>19</b>:148-154.</a></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com1tag:blogger.com,1999:blog-6094038346173044955.post-21128442730261179362022-11-16T20:02:00.000-05:002022-11-16T20:02:44.616-05:00Acanthobdella peledina<div style="text-align: left;">In the cold rivers and lakes of the arctic and subarctic region, there live some rather peculiar worms with a face full of tiny hooks and an appetite for blood. These worms live as ectoparasites of fish, and they belong to a group called <b>Acanthobdellida</b> - relatives of leeches that seem to have gone down their own evolutionary path. These worms have also been called "hook-faced fish worms" and the entire group consists of only two known species - <i>Acanthobdella peledina</i> and <i>Paracanthobdella livanowi</i>. </div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOUuEaNSIphj3vLn9EcTPqTs19gK74Qag0ytArQai0PlIUpdSuTDW7OsNx72Dyf3rpBo4Ta9ASyrxhCaGgDIvxE3Sz-nkG0V-0efz6hoEFCfajVpa06kvfaJ5vXJlws9rt72DJxgUidpFrkqN7Uq9SWUcYc48Ji5IVV_vkApnwtt7n8ub7AJMRlXSE/s1204/Acanthobdella%20peledina.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1078" data-original-width="1204" height="574" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOUuEaNSIphj3vLn9EcTPqTs19gK74Qag0ytArQai0PlIUpdSuTDW7OsNx72Dyf3rpBo4Ta9ASyrxhCaGgDIvxE3Sz-nkG0V-0efz6hoEFCfajVpa06kvfaJ5vXJlws9rt72DJxgUidpFrkqN7Uq9SWUcYc48Ji5IVV_vkApnwtt7n8ub7AJMRlXSE/w640-h574/Acanthobdella%20peledina.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Top: <i>Acanthobdella peledina </i>on a grayling. <br />Bottom: Scanning electron micrograph of the whole worm (left) and close-up of the anterior body region (right).<br />Photos from Figure 1, 6, and 7 of <a href=" https://academic.oup.com/zoolinnean/article-abstract/196/1/149/6645359">the paper</a></td></tr></tbody></table><br /><div>Their mouthpart has been described as being a less sophisticated version of a leech's mouthpart - they lack the saw-edged jaws or the extensible proboscis found in many leeches, nor do they have the muscular sucker which surrounds the mouth. Instead, they have a protrusible pharynx and a series of hooks on the first five segments of the body, which they use to attach themselves to their fishy hosts. </div><div><br /></div><div>They have previously been considered to be a "missing link" between leeches and the rest of the <b><a href=" https://en.wikipedia.org/wiki/Clitellata">Clitellata</a></b> - the group of segmented worms that also includes earthworms and <a href="https://en.wikipedia.org/wiki/Tubifex ">tubifex</a> worms - as they have certain features which are commonly found in other clitellate worms but are absent in leeches. This includes having tiny bristles (called <a href=" https://en.wikipedia.org/wiki/Chaeta">chaeta</a>) on their segments, and a reproductive system similar to those found in earthworms.</div><div><br /></div><div><i>Acanthobdella peledina</i> is found all across the subarctic, where they range from being relatively rare to being found on over two-thirds of the fish at a given location. Given it is so widely distributed, with populations scattered across different geographical locales, could each of those distinct populations actually be different species? A group of researchers set out to determine whether there are actually more species of these hook-faced worms than meets the eye. Furthermore, they also wanted to find out how closely related <i>Acanthobdella</i> and <i>Paracanthobdella</i> are to each other. They did so by comparing museum specimens of hook-faced worms which have been collected from sites across the subarctic, including Norway, Sweden, Finland, Alaska, and Russia. </div><div><br /></div><div>Aside from examining their anatomical features, the researchers also compared five different key marker genes from these worms. Some of those DNA segments came from the mitochondria, others from the cell's nucleus. The reason for comparing multiple genes is that each has their own histories, and may offer different perspectives on the organism's evolutionary history. It is like interviewing different witnesses at a crime scene. Unfortunately, for whatever reasons, the DNA of these worms proved to be particularly challenging to amplify and sequence, so for most specimens they were only able to sequence up to four of the five genetic markers they were aiming for, with some specimens only yielding sequences for two of the genes. Despite that limitation, the researchers were able to use the sequences they obtained to resolve the hook-faced worm's evolutionary history.</div><div><br /></div><div>Despite their wide distribution across the arctic and subarctic regions, <i>Acanthobdella peledina</i> does appear to be a single, widespread species. While the Alaskan population of worms are genetically distinct from the Nordic population, they are not dissimilar enough for them to be considered as separate species. Furthermore, based on their analysis, the two living species of hook-faced worms are quite closely related to each other. In fact, it seems they had only diverged from each other just prior to the last ice age. So, far from being some kind of "missing link" between leeches and other clitellate worms, these hook-faced worms belong to their own distinct group.</div><div><br /></div><div>But while the two living species had shared a common history until relatively recently, the hook-faced worms as a group had evolutionarily split off from the leeches a long time ago. Based on available data on these worms, this might have occurred <a href="https://academic.oup.com/gbe/article/11/11/3082/5520445 ">during the early Cenozoic</a> as the ancestors of the hook-faced worms became specialised on arctic freshwater fishes that arose during that era, such as salmonids.</div><div><br /></div><div>So it might have been the pursuit of salmonids that had sent these worms down their own distinct path - a story which is probably relatable to any fly fishers out there.</div><div><br /></div><div>Reference:</div><div>de Carle, D. B., Gajda, Ł., Bielecki, A., Cios, S., Cichocka, J. M., Golden, H. E., Gryska, A. D., Sokolov, S., Shedko, M. B., Knudsen, R., Utevsky, S., Świątek, P. & Tessler, M. (2022). Recent evolution of ancient Arctic leech relatives: systematics of Acanthobdellida. <i>Zoological Journal of the Linnean Society</i> <b>196</b>: 149-168.</div><div><br /></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-35610137467713392422022-10-18T19:08:00.000-04:002022-10-18T19:08:23.080-04:00Prochristianella sp.<div style="text-align: left;"><div>Earlier this year, I wrote about <i><a href=" http://dailyparasite.blogspot.com/2022/04/aggregata-sinensis.html">Aggregata sinensis</a> </i>a species of single-celled apicomplexan parasite that infects octopus. But octopuses are host to a wide range of other parasites as well, especially parasitic worms. Most of these worms infect the octopus during their larval stage, and use the cephalopod as a way to travel up the food chain to their final host - usually predatory vertebrate animals such as sharks, birds, and marine mammals. <i>Prochristianella</i> is one such parasite.</div><div><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzKb3f7uH7RlB4IbBwM1SgKiud4k7EFAcO4zoPQIu3ffGkojW5BTsUa8QIKO4j-WteW6k3c3mh9xESoFRRHBaddst0aAWxcEM8TFR5acLcSqsIjCzt47Afq3MWxr0Hyu7K2jTOV2vq9fzdqja9BXIGDGJs-gpZe3B-aFlgCWXThvYkuwI0GV-F65qa/s1197/Prochristianella.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1063" data-original-width="1197" height="568" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzKb3f7uH7RlB4IbBwM1SgKiud4k7EFAcO4zoPQIu3ffGkojW5BTsUa8QIKO4j-WteW6k3c3mh9xESoFRRHBaddst0aAWxcEM8TFR5acLcSqsIjCzt47Afq3MWxr0Hyu7K2jTOV2vq9fzdqja9BXIGDGJs-gpZe3B-aFlgCWXThvYkuwI0GV-F65qa/w640-h568/Prochristianella.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Left: A stained specimen of <i>Prochristianella</i> metacestode, Right top: Scanning electron microscopy of a <i>Prochristianella</i> metacestode, Right bottom: Scanning electron microscopy close-up of the <i>Prochristianella</i> scolex with protruding tentacles<br />Photos from Fig 2 and Fig 3 of the paper.</td></tr></tbody></table><br /><div>The paper being featured in this blog post focused on <i><a href=" https://en.wikipedia.org/wiki/Octopus_maya">Octopus maya</a></i>, also known as the Mexican four-eyed octopus, of the Yucatán Peninsula. It is a popular species for commercial fisheries both caught from the wild and in <a href=" https://en.wikipedia.org/wiki/Octopus_aquaculture">aquaculture</a>. Since it is such a widely fished and commonly eaten species, it would be a good idea to know just what kind of parasites are present in these octopus. The researchers obtained sixty <i>O. maya</i> from local fishermen in Mexico who have caught octopuses from four locations in Yucatán - <a href="https://en.wikipedia.org/wiki/Sisal,_Yucat%C3%A1n">Sisal</a>, <a href="https://en.wikipedia.org/wiki/Progreso,_Yucat%C3%A1n">Progreso</a>, <a href="https://en.wikipedia.org/wiki/Dzilam_de_Bravo_Municipality">Dzilam de Bravo</a>, and <a href="https://en.wikipedia.org/wiki/R%C3%ADo_Lagartos">Río Lagartos</a>. These cephalopods were caught using a <a href="https://demersais.furg.br/images/producao/2020_Sauer_et_al_World_Octopus_Fisheries_Reviews_in_Fish_Sc_Aq.pdf">tradition line fishing technique</a> <a href="https://biblioteca.ecosur.mx/cgi-bin/koha/opac-detail.pl?biblionumber=000058244">called <i><b>al garete</b></i></a><b><i> </i></b>where multiple lines of hooks baited with crabs are dangled from a small drifting boat and dragged along by the current.</div><div><br /></div><div>When the researchers dissected the octopuses, they found <b>seven</b> different types of tapeworm larvae in total, each occupying a different part of the octopus' body. Some were found in the intestine, others in the digestive glands, some were in the gills, and there were even some species that hung out in the ink sac. By far the most common species was <i>Prochristianella</i>, it was present at all four collection sites and was found in every single octopus the researchers examined. This tapeworm specifically occupied the octopus' buccal mass - the ball of muscles and connective tissue that houses the octopus' mouth. Not only was it common, <i>Prochristianella</i> was also extremely abundant, with each octopus having on average over a hundred <i>Prochristianella</i> larvae embedded in their buccal mass, while the octopus from Río Lagartos had over a thousand such tapeworms each. </div><div><br /></div><div>In fact, Río Lagartos seems to be tapeworm central, as that is also the location where the other six species of tapeworms also reach their highest prevalence and abundance. Perhaps it has something to do with Río Lagartos being located at the Ria Largatos lagoon, which is part of a nature reserve. Higher level of biodiversity can facilitate the transmission of parasites such as marine tapeworms, which need to use many different species of host animals to complete their complex life cycles.</div><div><br /></div><div><i>Prochristianella</i> was one of four types of trypanorhynch tapeworms found in the octopus. These tapeworms need to infect elasmobranch fishes such as sharks and rays to complete their life cycle, and the octopus, being prey to those fishes, is a convenient way for these parasites to get there. One of the unique features of trypanorhynch tapeworms is their attachment mechanism. Unlike other tapeworms with their hooks and suckers, the scolex of trypanorhynchs are armed with gnarly hook-lined tentacles, which shoot out like harpoons to anchor themselves into the intestinal wall of their elasmobranch host.</div><div><br /></div><div>One of the possible reasons why <i>Prochristianella</i> is so common and numerous among those octopuses is because it uses shrimps as one of the intermediate hosts in its life cycle. Octopus feed on shrimps throughout their entire life, so even if the tapeworm is relatively uncommon in shrimps, they can accumulate in the octopus over its lifetime. That's how those octopus end up with over a hundred or even a thousand such tapeworm larvae around their mouth.</div><div><br /></div><div>The next most common tapeworm in those octopus after <i>Prochristianella</i> was another trypanorhynchan tapeworms called <i>Eutetrarhynchus</i>, found in the digestive glands and ink sac. Though not as widespread or abundant as <i>Prochristianella</i>, it is still fairly common throughout the Yucatán Peninsula. The rest of the tapeworms is a smattering of different species, and while all of them complete their life cycles and develop into adult worms in sharks and rays, the path that they take to get there varies slightly. Some of the rarer species in this study usually use other animals such as bony fishes as intermediate or paratenic (transport) hosts, and occasionally end up in octopuses. While others, such as <i>Phoreiobothrium</i>, infect a wide range of different cephalopods, and <i>O. maya</i> just happen to be one of many potential hosts on their list. Overall, while they varied in abundance at different locations, these same set of tapeworms were present in octopus across the Yucatán Peninsula.</div><div><br /></div><div>The variety of tapeworms and other parasites found in <i>O. maya</i> shows that this cephalopod is an important junction point in the life cycles of many parasites. Being predators in their own right, octopuses end up accumulating parasite larvae which would otherwise be thinly dispersed throughout the population of small prey animals, such as shrimps. Meanwhile, octopus themselves are eaten by a wide variety of larger animals, thus providing the means for some parasites to work their way up the food chain, into large marine predators such as sharks where they can complete their life cycles. </div><div><br /></div><div>Through their parasites, we can see how these octopuses interact with other animals and their place in the wider marine ecosystem.</div><div><br /></div><div>Reference:</div><div><a href="https://www.sciencedirect.com/science/article/pii/S2213224422000724">Marmolejo-Guzmán, L. Y. G., Hernández-Mena, D. I. G., Castellanos-Martínez, S., & Aguirre-Macedo, M. L. (2022). Linking phenotypic to genotypic metacestodes from Octopus maya of the Yucatan Peninsula. <i>International Journal for Parasitology: Parasites and Wildlife</i> <b>19</b>: 44-55.</a></div></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-3590158400396048032022-09-20T08:15:00.000-04:002022-09-20T08:15:55.476-04:00Hymenoepimecis bicolor<div style="text-align: left;">Over the course of human history, numerous species of plants, animals, and other organisms have been taken from their original habitats and introduced (either intentionally or accidentally) to other parts of the world. Some of those introduced species become "<a href="https://en.wikipedia.org/wiki/Invasive_species">invasives</a>" in their new home, partly due to the <a href="https://en.wikipedia.org/wiki/Enemy_release_hypothesis">lack of natural enemies</a>. But while many invasive species get a brief moment of respite from their old adversaries, the local parasite and predators quickly catch on that the new arrival could be added to their menus too. This was the case for a species of spider that has been introduced to Brazil, where it ended up attracting the attention of a mind-controlling wasp.</div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtdIjFUB1KNi5h8_I7_ak8-zbcesd0qYvV-C0mUMYSWcWgRaCkrpChN_vV5r4B--Z1NN1VjRnjlnP03CleVHwkB5iqMpcNht2F2KZC0HHh3KVsd21gvn102IOV0KaWNrEfHXaw3cdieZJ8Cxxt5G9SvIARMOAnOitm0MvARofQoEinsM-6OJ23rOKc/s1731/Hymenoepimecis%20bicolor.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1077" data-original-width="1731" height="398" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtdIjFUB1KNi5h8_I7_ak8-zbcesd0qYvV-C0mUMYSWcWgRaCkrpChN_vV5r4B--Z1NN1VjRnjlnP03CleVHwkB5iqMpcNht2F2KZC0HHh3KVsd21gvn102IOV0KaWNrEfHXaw3cdieZJ8Cxxt5G9SvIARMOAnOitm0MvARofQoEinsM-6OJ23rOKc/w640-h398/Hymenoepimecis%20bicolor.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Left top: <i>Hymenoepimecis bicolor</i> larva on a spider host, Left bottom: Developing <i>H. bicolor </i>cocoon in a cocoon web, <br />Right: an adult <i>H. bicolor</i> wasp. <br />Photo of <i>H. bicolor </i>larva from Fig. 2 of <a href="https://www.tandfonline.com/doi/full/10.1080/03949371003707836">this paper</a>, Photos of cocoon and adult <i>H. bicolor </i>from Fig. 7 and 9 of <a href="https://jhr.pensoft.net/article/76620/">this paper</a></td></tr></tbody></table><br /><div style="text-align: left;"><i>Hymenoepimecis bicolor</i> is a species of parasitoid wasp that belongs to a subfamily of wasps called <a href="https://en.wikipedia.org/wiki/Pimplinae">Pimplinae</a>. All the members of that subfamily are a spider's worst nightmares. These wasps specialise in attacking spiders at every stage of their lives - some species go after the unhatched eggs in silk sacs, while others tackle fully-grown adult spiders. Not only that, some of them are also masterful mind manipulators that induce their host spider into s<a href=" https://jhr.pensoft.net/article/14817/">pinning a special web</a> called a "<a href=" https://www.tandfonline.com/doi/abs/10.1080/00222930903244010">cocoon web</a>" that secures the wasp's developing cocoon. And <i>Hymenoepimecis bicolor</i> just happens to be <a href="https://www.tandfonline.com/doi/full/10.1080/03949371003707836">one such manipulator</a>.</div><div><br /></div><div>Among the pimpline wasps, each species have their own host preferences and in the case of <i>H. bicolor</i>, one of its usual hosts is the golden silk orb-weaver (<i><a href="https://en.wikipedia.org/wiki/Trichonephila_clavipes">Trichonephila clavipes</a></i>), a spider which is native to Brazil. When a female <i>H. bicolor</i> spots a potential host, she flies in and grapples with it, immobilising the spider by stabbing it in the mouth with her ovipositor, before checking it for other wasp eggs, and then planting one of her own. The thing about the golden silk orb-weaver is that while the juvenile spiders are relatively easy for <i>H. bicolor </i>to handle, once the spiders reach adulthood, they become more dangerous for the wasp to tackle. </div><div><br /></div><div>Nevertheless, limited host availability means that the wasp sometimes need to go after the bigger spiders anyway, with demand being so high that some spiders end up being parasitised by two wasp larvae at the same time. But the arrival of the tropical tent-web spider (<i><a href="https://en.wikipedia.org/wiki/Cyrtophora_citricola">Cyrtophora citricola</a></i>) has provided <i>H. bicolor</i> with some new options.</div><div><br /></div><div>The tropical tent-web spider has spread to many parts of the world by <a href=" https://link.springer.com/article/10.1007/s10530-015-0912-5">hitchhiking</a> in shipments of fruit, potted plants, or packing material, and it has <a href="https://assets.researchsquare.com/files/rs-572646/v1/26aa5f70-6fa4-4b6a-afde-7b62ae13f449.pdf">made its way to South America </a>about three decades ago. And it just so happens that their size and habits place them firmly in the sight of <i>H. bicolor</i>. Not only is the tent-web spider in the preferred size range for <i>H. bicolor </i>to parasitise, much like the native orb-weavers, this introduced spider constructs open webs that leave them exposed to attacks. Researchers found that the <i>H. bicolor</i> larvae are able to successfully parasitise the tent-web spider just as well as the native spiders.</div><div><br /></div><div>While <i>H. bicolor</i> larvae grow well and pupate as usual on the tent-web spiders, it seems that they haven't yet achieved complete mastery over this new-fangled host. As mentioned earlier, when these wasps are ready to pupate, they commandeer their spider hosts to weave a special "cocoon web" that suspends the developing wasp cocoon in mid-air. This makes the cocoon less accessible to any would-be predators or hyperparasitoids. <i>Hymenoepimecis bicolor</i> embellish that with an added layer of security, by inducing the spider to also build a series "barrier threads" around the cocoon that further bar entry, as well as making the web more stable</div><div><br /></div><div>This is where the introduced spider host falls short. While the parasitised tent-web spider is able to produce the usual cocoon web with the necessary structure to support and suspend the developing cocoon, it lacks the finishing touches of those additional barrier threads. Ironically, compared with the spiders that <i>H. bicolor</i> usually targets, the regular webs made by the tent-web spider actually needs <i>less</i> modification to make it suitable for the wasp's cocoon.</div><div><br /></div><div>Based on what's known about these wasps, when it is ready to pupate, the wasp larva produces a cocktail of chemicals that place the spider under its spell. But in this case, it looks like that cocktail formula needs a bit of tweaking to work its full magic on the introduced tent-web spider. While not perfect, it serves its purpose well enough, and the introduction of this spider has allowed a parasitoid wasp to expand its host horizons.</div><div><br /></div><div>Reference:</div><div><a href="https://jhr.pensoft.net/article/76620/">Gonzaga, M. O., Pádua, D. G., & Quero, A. (2022). Inclusion of an alien species in the host range of the Neotropical parasitoid <i>Hymenoepimecis bicolor</i> (Brullé, 1846)(Hymenoptera, Ichneumonidae). <i>Journal of Hymenoptera Research</i> <b>89</b>: 9-18.</a></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-33799515460588115702022-08-14T06:55:00.000-04:002022-08-14T06:55:44.959-04:00Cyclocotyla bellones<div style="text-align: left;">At the top of this blog, there is a quote by Jonathan Swift about how fleas have smaller fleas that bite them. Indeed, parasites becoming host to other types of parasites is actually a rather common phenomenon in the natural world. Those who would parasitise the parasites are called "<b><a href="http://dailyparasite.blogspot.com/search/label/hyperparasite">hyperparasites</a></b>".</div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwq89xXQUF_sPn5emsKYAZ_rXVmedkBmMFMJ-LwXZR4gXs31mbdtH9lzoKo_4SC8o62QpkEXnXXobcW7nR0zVGgYcRLk_AmikqTXR7S0LbC8Oor6E8xApFAhQ0NWrD8Tu9bIBhXiwbrvz0WjEZQochLOBxKIGXV7Cj9aPutU_W8cJqOiGkw-9E98Lp/s1589/Cyclocotyla%20bellones.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1067" data-original-width="1589" height="430" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwq89xXQUF_sPn5emsKYAZ_rXVmedkBmMFMJ-LwXZR4gXs31mbdtH9lzoKo_4SC8o62QpkEXnXXobcW7nR0zVGgYcRLk_AmikqTXR7S0LbC8Oor6E8xApFAhQ0NWrD8Tu9bIBhXiwbrvz0WjEZQochLOBxKIGXV7Cj9aPutU_W8cJqOiGkw-9E98Lp/w640-h430/Cyclocotyla%20bellones.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Left: <i>Cyclocotyla bellones </i>on the back of a <i>Ceratothoa </i>isopod, Right: <i>C. bellones </i>coloured red with Carmine staining.<br />Photos from Figure 1 and 5 of the paper.</td></tr></tbody></table><br /><div>The parasite featured in this post was once suspected of being a hyperparasite. <i>Cyclocotyla bellones</i> is a species of <a href="https://en.wikipedia.org/wiki/Monogenea">monogenean</a> - it belongs to a diverse group of parasitic flatworms that mostly live on the body of fish, parasitising the fins, skins, and gills of their hosts. But unlike other monogeneans, <i>C. bellones</i> does not attach itself to any part of a fish's body, instead it prefers to stick its suckers onto the carapace of parasitic isopods, such <i>Ceratothoa</i> - the infamous tongue biter. Since <i>Ceratothoa</i> is itself a fish parasite, and <i>C. bellones</i> is routinely found attached to those tongue-biters, this has led some to think that it might be a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8183466/">hyperparasite of those parasitic crustaceans</a>.</div><div><br /></div><div>But it takes more than simply sticking yourself onto another organism to be considered as a parasite of it. After all, there are algae that grow on the body of various aquatic creatures, or barnacles that are found on the backs of large marine animals like whales and turtles. But those are not considered as parasites as they don't treat their host as a food source, merely as a sturdy surface they can cling to - they're known as <b><a href=" https://en.wikipedia.org/wiki/Epibiont">epibionts</a></b>.</div><div><br /></div><div>So strictly speaking, for <i>Cyclocotyla</i> to be a parasite of the isopod, it needs to be feeding on or obtaining its nutrient directly from its isopod mount. When scientists examine the bodies of the tongue-biters with <i>C. bellones</i> on them, they seem to be pretty unscathed. There aren't any scratches or holes on the isopod's body which you'd expect if <i>C. bellones</i> had been feeding on it. Indeed, the monogenean's mouthpart seems ill-suited for scraping through the isopod's carapace.</div><div><br /></div><div>Additionally, <i>C. bellones</i>' gut is filled with some kind of dark substance similar to those found in other, related monogenean species. This is most likely digested blood from the fish, which the monogenean has either sucked directly from the fish's gills, or indirectly via the feeding action of its isopod mount. Let's not forget that the isopod itself is a fish parasite that feeds on its host's blood, so if it gets a bit messy during mealtime, perhaps <i>Cyclocotyla</i> is there to suck up any spilled blood. Or it might be doing a bit of both.</div><div><br /></div><div>The researcher noted that <i>Cyclocotyla</i> is not alone in its habit of riding isopods. Other monogeneans in its family (<b>Diclidophoridae</b>) have also been recorded as attaching to parasitic isopods of fish. And aside from riding isopods, they all share one thing in common - a long, stretchy forebody, looking somewhat like the neck of sauropod dinosaurs. Much like how the neck of those dinosaurs allowed them to browse vegetation from a wide area, the long forebody of <i>Cyclocotyla</i> allows it to graze on the fish's gills while sitting high on the back of an isopod. So fish blood is what <i>C. bellone</i> is really after - the isopod is merely a convenient platform for it to sit on.</div><div><br /></div><div>But why should these monogeneans even ride on an isopod in the first place? <i>Cyclocotyla</i> and others like it have perfectly good sets of suckers for clinging to a fish's gills. Indeed, there are other similarly-equipped monogeneans that live just fine as fish ectoparasites without doing so from the back of an isopod. Well, that's because the fish themselves don't take too kindly to the monogeneans' presence. These flatworms are constantly under attack from the <a href=" https://www.sciencedirect.com/science/article/pii/S0020751901003320 ">fish's immune system</a>, which bombards them with all kinds of enzymes, antibodies, and immune cells. By avoiding direct contact with the fish's tissue, <i>Cyclocotyla</i> and other isopod-riders can avoid being ravaged by the host's immune system - which is something that other <a href=" https://www.sciencedirect.com/science/article/pii/S1050464820305878 ">monogeneans have to deal with</a> on a constant basis.</div><div><br /></div><div>So it seems that <i>Cyclocotyla</i> and other isopod-riding monogeneans are no hyperparasites - they're all just regular fish parasites that happen to prefer doing so while sitting on the backs of isopods. <i>Cyclocotyla bellones</i> prefers to share in the feast of fish blood with its isopod mount, while sitting high above the wrath of the host's immune response.</div><div><br /></div><div>Reference:</div><div><a href=" https://www.parasite-journal.org/articles/parasite/abs/2022/01/parasite210152/parasite210152.html">Bouguerche, C., Tazerouti, F., & Justine, J. L. (2022). Truly a hyperparasite, or simply an epibiont on a parasite? The case of <i>Cyclocotyla bellones</i> (Monogenea, Diclidophoridae). <i>Parasite</i> <b>29</b>: 28.</a></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-64026993704235723332022-07-18T19:51:00.000-04:002022-07-18T19:51:10.867-04:00Dolichoperoides macalpini<div style="text-align: left;">Australia has some of the most venomous snakes in the world, but the mouths of those reptiles are filled with more than just venomous fangs. In some cases, they are filled with tiny digenean flukes, specifically <i>Dolichoperoides macalpini</i>. This species of fluke was first reported from the lowland copperhead snakes in the 1890s, but it wasn't until 1918 that it was formally identified and described, and in 1940 it was placed in its own genus when it was recognised that it was specifically associated with elapid snakes. Since then, there hasn't been much further studies on this fluke, and the research team behind the paper in this post seeks to fill in that knowledge gap.</div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJyZCDCX6mUIKkOQQY41x21aTTC7uA1P-6SMw8aIYRbjVq9cvY2OAJXYc1dCoYf5YroRa1-2BjrOGZ_PP5PpIdZYwf0A6JVmmxGbVGBLWr6Mtc_9wFrgGe77O6Aqroaa0bwaggNPo8YDrx9oPOdIJdVzyxe7fx0jjSZJxUZ9JQXMOPxEWW1G4vobhs/s1504/Dolichoperoides%20macalpini.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="821" data-original-width="1504" height="350" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJyZCDCX6mUIKkOQQY41x21aTTC7uA1P-6SMw8aIYRbjVq9cvY2OAJXYc1dCoYf5YroRa1-2BjrOGZ_PP5PpIdZYwf0A6JVmmxGbVGBLWr6Mtc_9wFrgGe77O6Aqroaa0bwaggNPo8YDrx9oPOdIJdVzyxe7fx0jjSZJxUZ9JQXMOPxEWW1G4vobhs/w640-h350/Dolichoperoides%20macalpini.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Left: <i>Dolichoperoides macalpini </i>in a snake's mouth, Right: <i>Dolichoperoides macalpini </i>in a snake's lungs<br />Photos from Fig. 1 of the paper</td></tr></tbody></table><br /><div>For this study, the researchers collected snakes from parts of Tasmania and Western Australia.</div><div>In Tasmania, they collected roadkills composed of Tiger Snake (<i><a href=" https://australian.museum/learn/animals/reptiles/tiger-snake/">Notechis scutatus</a></i>) and Lowland Copperhead (<i><a href=" https://en.wikipedia.org/wiki/Lowland_copperhead">Austrelaps superbus</a></i>). While in Western Australia, they obtained freshly caught and euthanised Western Tiger Snake (<i>Notechis scutatus occidentalis</i>) which were collected as a part of another, larger project examining tiger snakes from wetlands in and around <a href="https://en.wikipedia.org/wiki/Perth">Perth</a>. <i>Dolichoperoides macalpini</i> were mostly found in the snake's mouth, oesophagus, and stomach. And when the snake's mouth is open, the flukes are clearly visible as tiny black specks that clung to the roof of the snake's mouth (see accompanying photo). However, the snakes from Tasmania had <i>D. macalpini</i> in their lungs and intestine as well. So what's going on there? </div><div><br /></div><div>This could be because the snake specimens examined in Tasmania were roadkills. In some cases, after the host dies, its parasites may move from their usual location to different parts of the host's body, possibly due to some last ditch survival instincts. This phenomenon is well-known in anisakid nematodes, which is a major seafood-borne zoonotic parasite. After their fish host is caught, these worms <a href=" https://www.sciencedirect.com/science/article/abs/pii/0020751975900193">often migrate from their host's viscera</a> <a href=" https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8691968/">to its flesh</a>. In the case of <i>D. macalpini</i>, once they sense that their host had died, perhaps they evacuated away from the mouth and throat to other, deeper parts of the body such as the lungs and intestine in a desperate bid for survival.</div><div><br /></div><div>This may also explain some of the other differences the researchers found in the infection patterns of different snake populations. The Tassie snakes generally had fewer flukes than those which were caught around Perth. Since the Tasmanian snakes were found as roadkill, it is possible that the flukes which didn't crawl to the lungs or intestine had just ended up abandoning the snake altogether.</div><div><br /></div><div>But this difference in fluke abundance may have also been influenced by other more innate factors of the snakes' ecologies. The encysted larval stage of <i>D. macalpini</i> are found in frogs, which the Perth snakes were particularly fond of, with frogs accounting for almost 90% of their diet. This provided them with ample opportunities to encounter the infective larval stages of <i>D. macalpini</i> through their food. In contrast, the Tassie snakes had a more varied diet consisting of rodents, birds, and lizards - but no frogs.</div><div><br /></div><div>Additionally, there were also other differences among the flukes themselves. For example, while the snakes from Perth were more heavily infected, their flukes were only about half the size of those found in the Tasmanian snakes. While such size differences might have indicated that the flukes in those separate snake populations may in fact be different species, genetic analyses showed otherwise. The <a href="https://en.wikipedia.org/wiki/18S_ribosomal_RNA">18S rRNA gene</a> and <a href="https://en.wikipedia.org/wiki/Internal_transcribed_spacer">ITS gene</a> sequences - which are key genetic markers for delineating different species among these parasites - were identical for the flukes from both Tasmanian and Perth snakes.</div><div><br /></div><div>So there must be other reasons for such marked differences in their sizes. Perhaps in more heavily infected hosts, the crowded environment may have limited the flukes' growth? Studies on other species of flukes have found that those from <a href="https://www.cambridge.org/core/journals/journal-of-helminthology/article/abs/causes-of-intraspecific-variation-in-body-size-among-trematode-metacercariae/9068133CE156B5D20E6AD038CCC6D06E">more heavily infected hosts </a><a href="https://meridian.allenpress.com/journal-of-parasitology/article-abstract/86/5/1056/6007/DEVELOPMENT-AND-INTENSITY-DEPENDENCE-OF">tend to be smaller on average </a>than their counterparts from less parasitised hosts. This diminished growth may be the result of competition over limited resources, be it host nutrient, or simply available space for growth. Or perhaps there are slight variations between the biology of different snake species that can influence the fluke's growth?</div><div><br /></div><div>The result of this study offers a brief glimpse into the distribution and infection patterns of <i>D. macalpini</i> in Australian snakes, and it raises some tantalising questions about the parasite's ecology. But there are many other reptile parasites in Australia for which little is known about them outside of a taxonomic description. Despite having one of the world's richest reptile fauna, the parasites fauna of Australian reptiles are relatively understudied. Not only are they an integral part of Australia's biodiversity, understanding these parasites can also tell us about how their reptile hosts are connect with the rest of the ecosystem.</div><div><br /></div><div>Reference:</div><div><a href="https://link.springer.com/article/10.1007/s00436-022-07502-x">Barton, D. P., Lettoof, D. C., Fearn, S., Zhu, X., Francis, N., & Shamsi, S. (2022). <i>Dolichoperoides macalpini</i> (Nicoll, 1914)(Digenea: Dolichoperoididae) infecting venomous snakes (Elapidae) across Australia: molecular characterisation and infection parameters. <i>Parasitology Research</i> <b>121</b>: 1663-1670.</a></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com1tag:blogger.com,1999:blog-6094038346173044955.post-11667360233970212572022-06-18T20:13:00.000-04:002022-06-18T20:13:35.820-04:00Sarcotaces izawai<div style="text-align: left;"><div>Parasitic copepods are a <a href=" http://dailyparasite.blogspot.com/2019/06/pennella-instructa.html">weird bunch</a>, <a href=" http://dailyparasite.blogspot.com/2013/06/urogasilus-brasiliensis.html">and many</a> <a href=" https://twitter.com/The_Episiarch/status/1436504227967168522">of them</a> <a href=" https://twitter.com/The_Episiarch/status/1466960962271858690">look nothing</a> <a href="https://twitter.com/The_Episiarch/status/1131378052770873345">like what most people would recognise as a crustacean</a>. But even among those weirdos, <i><a href="https://www.flickr.com/photos/dryodora/172618526">Sarcotaces</a></i> stands out, because during the course of its evolution, it has turned into a <a href="https://www.flickr.com/photos/dryodora/3608878449/">big teardrop-shaped blob</a> living inside a fish's body.</div><div><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggNW1EQ86nPYzZy7I5l_Ap4nsa_ALc_9ECidTy6i6AgJZIo6vZYA1CkdqNryVjKEUvatgQ1gWUvg4mQmMLp8uW4-oo9RrkuY9H4ueVwDY3tAkBQWaDdpaYUHBWG3e0cYQpFBi3jbhnsBF-ox8gJ9d0JGRwyXPwZ506ip-PUve4TrjTEXrIu-uBwS-D/s1361/Sarcotaces%20izawai.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1075" data-original-width="1361" height="506" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggNW1EQ86nPYzZy7I5l_Ap4nsa_ALc_9ECidTy6i6AgJZIo6vZYA1CkdqNryVjKEUvatgQ1gWUvg4mQmMLp8uW4-oo9RrkuY9H4ueVwDY3tAkBQWaDdpaYUHBWG3e0cYQpFBi3jbhnsBF-ox8gJ9d0JGRwyXPwZ506ip-PUve4TrjTEXrIu-uBwS-D/w640-h506/Sarcotaces%20izawai.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Top left: Staining of the fish body due to <i>Sarcotaces</i>, Top right: <i>Sarcotaces </i>extracted from fish flesh<br />Left: A Female <i>Sarcotaces </i>specimen (about 4 cm in length)<br />Photos from Fig. 1 and Graphical Abstract of the paper.</td></tr></tbody></table><br /><div>There are seven known species of <i>Sarcotaces</i>, all of which are parasites that dwell in fleshy galls embedded in the muscles of fish. The female of the species can grow up to about 5 cm long. They belong to a family of copepods called <b>Philichthyidae</b> which all specialise in living within nooks and crannies of a fish's body, including their skull, sensory canals, or inside galls just beneath the fish's skin. The study featured in this blog post described a newly discovered species of <i>Sarcotaces</i> - <i>Sarcotaces izawai</i>.</div><div><br /></div><div>Specimens of <i>S. izawai </i>were retrieved from a consignment of frozen fish which were originally destined for the fish market, but were redirected to researchers when the County Veterinary Inspector of Szczecin noticed signs of infection in some of the fish. In total, 29 fish were taken to the University of Szczecin for further examination. Nine of those fish were found to harbour the gall of <i>Sarcotaces</i> - where there was once fish muscle had been turned into a black void, a dark fleshy cavern where the female <i>Sarcotaces</i> resided alongside her tiny males and microscopic larvae.</div><div><br /></div><div>The black liquid associated with this copepod is what gave <i>Sarcotaces</i> its German name - "<i><b>Tintenbeutel</b></i>" which means "ink bag", and why in parts of Australia, they're called "<a href="https://www.amsa.asn.au/sites/default/files/AMSA%20Bulletin%20%2381.pdf">Iodine Worms</a>". Even in the other fish where no <i>Sarcotaces</i> were found, the fish's flesh were tainted with an ink-stained void, which most likely meant a <i>Sarcotaces</i> had once lived there, but was inadvertently removed when the fish were being processed. While the presence of this parasite does not pose any health hazards to any would-be consumers, the inky stain in the fish's flesh do render them off-putting to any would-be buyers on the market. But, because of this, the researchers were given an opportunity to conduct detailed scanning electron microscopy on the copepod, and provided the first DNA barcode for this unique genus of parasite based on <a href=" https://en.wikipedia.org/wiki/Cytochrome_c_oxidase_subunit_I#Use_in_DNA_barcoding">its COI gene</a>.</div><div><br /></div><div>While the female <i>S. izawai</i> is very distinct and noticeable, the male is rather inconspicuous - they grow to about 3 mm in length, and are comparatively tiny and fairly nondescript. In comparison, the female is shaped like a knobbly radish, and grows to 2.5 to 5 cm in length or 10-20 times the length of the male. This size difference is comparable to that of a human and a sperm whale. It also means that a single female could be accompanied by multiple males. Indeed, the researchers found one female who was accompanied by 18 suitors in her flesh gall.</div><div><br /></div><div>While very little is known about how the microscopic, free-swimming larvae of <i>Sarcotaces</i> gets into a fish in the first place, it seems that the growth and development of the female <i>Sarcotaces</i> takes place entirely within the sac-like gall. This flesh bag has a tiny opening to the outside world that the copepod usually keeps plugged using the pointy tip of her body, and unplugs to release larvae into the surrounding waters. Because of this, the researchers consider <i>Sarcotaces</i> as a "<b>mesoparasite</b>", because while they largely live within the fish's body, they still maintain some contact with the outside world with the tip of the body plugging up that hole.</div><div><br /></div><div>As an added layer to that study, the consignment of frozen fish that the researchers examined have been been frozen and thawed multiple times, and were "pan-dressed" - in that their head, fins, and the guts have been taken out - this might be why some of the fish had the characteristic inky stain of <i>Sarcotaces</i> even though the parasite was absent. This made the identification of those fish rather difficult simply through visual inspection. While the consignment of fish were labelled as <i><a href="https://www.fishbase.de/summary/Pseudophycis-bachus.html">Pseudophycis bachus</a> </i>- red codling - from "The Falklands", the researchers found this to be a case of <a href="https://www.aiep.pl/volumes/2020/1_4/pdf/09_02932_F2.pdf">seafood identity fraud</a>.</div><div><br /></div><div>When they did some DNA analyses they found that the fish were actually <i><a href="https://www.fishbase.de/summary/Mora-moro.html">Mora moro</a></i> - a species of deep sea cod which is found in temperate seas across many parts of the world, but has not been recorded from the Falklands. It is likely that the fish wholesalers were trying to use the mislabelling to bypass regional quotas or conceal catches from restricted waters.</div><div><br /></div><div>This type of seafood mislabelling is <a href="https://www.theguardian.com/environment/2021/mar/15/revealed-seafood-happening-on-a-vast-global-scale">very common around the world</a>, and presents problems for consumer protection, food safety and supply, fisheries regulations, and conservation. In this case, not only did the ink-stained fillets of these <i>Sarcotaces</i>-infected fish provide scientists with an opportunity to examine a poorly-understood parasite, the presence of this tubby copepod also helped draw attention to a case of seafood identity fraud.</div><div><br /></div><div>Reference:</div><div><a href="https://www.sciencedirect.com/science/article/pii/S221322442200027X">Piasecki, W., Barcikowska, D., Panicz, R., Eljasik, P., & Kochmański, P. (2022). First step towards understanding the specific identity of fish muscle parasites of the genus <i>Sarcotaces</i> (Copepoda: Philichthyidae)—New species and first molecular ID in the genus. <i>International Journal for Parasitology: Parasites and Wildlife</i> <b>18</b>: 33-44.</a></div></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com2tag:blogger.com,1999:blog-6094038346173044955.post-64366721110930073102022-05-20T01:03:00.001-04:002022-06-06T07:30:44.986-04:00 Guimaraesiella sp.<div style="text-align: left;">Quite a few years ago I wrote a blog post about a study on some bird lice that <a href=" http://dailyparasite.blogspot.com/2016/04/pseudolynchia-canariensis-revisited.html">hitch-hike on louse flies</a> as a way of reaching new hosts - this type of interaction whereby an organism attach itself to the body of another as a way of getting around is called "<a href="https://en.wikipedia.org/wiki/Phoresis">phoresy</a>". And while it is a fascinating interaction with important ecological implications, this phenomenon is not particularly well-studied. Well, the paper that is being featured in this blog post revisited that field of research, and used multiple approaches to investigate this type of interaction. And the researchers behind it did so by combining literature review, traditional parasitology, DNA barcoding, and citizen science.</div><div style="text-align: left;"><br /></div><div class="Ar Au Ao" id=":1ws"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzoHTFWEnVFqgTjOMF06YGNSgaZ0t86cYmsqrQz51AXzbc97yQrK05vtHKr7E0cYJP17x-aLTAe7TnNkbGSWozx65c9Jn7Rc8TegIV_i-tFwlHxQHy1QBUicNUHBJnwoJGPQMpbewHFXyVHLM5wXXVgWSByxehEA16904tbzplNdXTlbMi5UYsKaG2/s1920/Guimaraesiella%20sp.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1080" data-original-width="1920" height="360" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzoHTFWEnVFqgTjOMF06YGNSgaZ0t86cYmsqrQz51AXzbc97yQrK05vtHKr7E0cYJP17x-aLTAe7TnNkbGSWozx65c9Jn7Rc8TegIV_i-tFwlHxQHy1QBUicNUHBJnwoJGPQMpbewHFXyVHLM5wXXVgWSByxehEA16904tbzplNdXTlbMi5UYsKaG2/w640-h360/Guimaraesiella%20sp.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Left: Guimaraesiella lice found on from louse flies. Right: Louse fly with lice attached (indicated by red arrows). <br />From Figure 3 of the paper.<br /><br /></td></tr></tbody></table><div aria-label="Message Body" aria-multiline="true" class="Am Al editable LW-avf tS-tW tS-tY" g_editable="true" hidefocus="true" id=":1wo" role="textbox" spellcheck="false" style="direction: ltr; min-height: 245px;" tabindex="1">The researchers of this study were trying to figure out how common phoresy is among bird lice, and who exactly is hitch-hiking on what. They conducted a review of the existing scientific literature on phoretic relationships between lice and louse flies, and found that many of the older records were unusable because they lack sufficient details regarding species identity of the lice involved. Furthermore, while phoretic behaviour in lice is most well-documented in North America and Europe, there are other parts of the world with much richer avian fauna (and thus more bird lice species), but phoretic behaviour of bird lice in those regions are not as well-studied.<br /><br />To address this, the researchers came up with a way of collecting lice and louse flies from a large number of birds, and did so with some help from members of the public. As a part of long-term project to <a href=" http://www.jurnal.unsyiah.ac.id/IJTVBR/article/view/9528">monitor bird mortality</a> from vehicle and building collisions, ordinary citizens in Singapore were encouraged to report any dead birds that they come across. Through this, the researchers were able to track down and collect over a hundred recently deceased birds for this study. They then screened the dead birds for lice and louse flies, which were identified based on their morphology and their DNA.<br /><br />In total, they screened 131 birds composed of 54 different species, and collected 603 lice and 32 louse flies. Of those, 22 birds had louse flies on them, but only three of the louse flies also happened to be carrying hitch-hiking lice, which were identified as belonging to the genus <i>Guimaraesiella</i>. Amidst all that, they found something unexpected - one of the birds, a Blue-winged pitta (<i><a href="https://en.wikipedia.org/wiki/Blue-winged_pitta">Pitta moluccensis</a></i>) was infected with louse flies carrying <i>Guimaraesiella</i> lice. This is the first time that <i>Guimaraesiella</i> lice has been found on pittas, as those birds are usually infected with lice in the <i><a href=" https://phthiraptera.myspecies.info/category/chewing-lice/philopteridae/picicola">Picicola</a></i> genus.</div><div aria-label="Message Body" aria-multiline="true" class="Am Al editable LW-avf tS-tW tS-tY" g_editable="true" hidefocus="true" id=":1wo" role="textbox" spellcheck="false" style="direction: ltr; min-height: 245px;" tabindex="1"><br />It is likely that riding on louse flies is how <i>Guimaraesiella</i> ended up on the pitta. Indeed, lice in that genus appear to live on a wider range of birds compared with most bird lice, which are often confined to a single or handful of closely related host species, and its hitch-hiking habit may be the key to their success. While bird lice are very adept at climbing around and between their host's feathers, they are completely helpless off the host's body. This doesn't give them much opportunity to branch out and onto other bird species as they can only climb onto a new host through direct contact.<br /><br />But since louse flies feed on a variety of different bird hosts, travelling on one of those flying blood-suckers can open up a whole new world of possibilities for lice that engage in phoresy. The species of <i>Guimaraesiella</i> lice they found on the pitta has also been found on at least 24 other species of birds, possibly more. Considering that the louse fly that <i>Guimaraesiella</i> rides on - <i>Ornithophila metallica</i> - feeds from <a href="https://www.researchgate.net/publication/336177987_The_Louse_Flies_Ornithophila_metallica_Schiner_1864_and_O_gestroi_Rondani_1878_Diptera_Hippoboscidae_Distribution_and_Association_with_Birds_in_the_Palaearctic">over a hundred different bird genera</a>, perhaps it is surprising that <i>Guimaraesiella</i> hasn't been found from even <b>more</b> bird species. So while the louse fly presents its hitch-hiker lice with many different species of birds, those well-travelled lice still stay fairly selective when it comes to where they settle on. These lice are like Goldilocks when it comes to picking a new feathery home - it needs to be just the right fit.<br /><br />The approach taken by the researchers in this study to recover and screen large numbers of birds for louse flies and lice can also be applied to other parts of the world. This would help us obtain a more complete understanding of how widespread hitch-hiking lice actually are, and the role this behaviour has played in the evolution of these ectoparasitic insects.<br /><br />Reference:<br /><a href="https://resjournals.onlinelibrary.wiley.com/doi/full/10.1111/syen.12539">Lee, L., Tan, D. J., Oboňa, J., Gustafsson, D. R., Ang, Y., & Meier, R. (2022). Hitchhiking into the future on a fly: Toward a better understanding of phoresy and avian louse evolution (Phthiraptera) by screening bird carcasses for phoretic lice on hippoboscid flies (Diptera). <i>Systematic Entomology</i> <b>47</b>: 420-429.</a></div></div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-54865397089723101472022-04-21T09:44:00.000-04:002022-04-21T09:44:58.272-04:00Aggregata sinensis<div style="text-align: left;"><a href=" https://en.wikipedia.org/wiki/Apicomplexa">Apicomplexa</a> is a diverse phylum of single-celled parasites. They are found in a wide range of different animals, and includes some well-known species which can infect humans such as the malaria-causing <i>Plasmodium</i>, the infamous and widespread <i>Toxoplasma gondii</i>, and the gut-busting <i>Cryptosporidium</i>. But it is not as if this group has any particular affinity for humanity - humans are just one species among <b>many</b> across the animal kingdom that are hosts for apicomplexan parasites. Most of the more well-studied apicomplexans are those that infect terrestrial animals, especially domesticated species, but far less is known about apicomplexan parasites that are found in the marine realm.</div><div><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJiXovd5sGhLLc7q7Pr8juT1H9Fgd7F52fJzrDtXFh_IX2tlnBkMKanxn8csP5FL1gDMnEHKLP_n8gJRvFl9F3GF-VejGOJjSSVKMnVzUyp7lgmBN_bcECkc_yYrA-PTSvN56I_IHLYng0lFP_ELUlPmfdWd_CJZ6sVMOEDzfHj8tVyXirUfJGH7qF/s1214/Aggregata%20sinensis.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1082" data-original-width="1214" height="570" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJiXovd5sGhLLc7q7Pr8juT1H9Fgd7F52fJzrDtXFh_IX2tlnBkMKanxn8csP5FL1gDMnEHKLP_n8gJRvFl9F3GF-VejGOJjSSVKMnVzUyp7lgmBN_bcECkc_yYrA-PTSvN56I_IHLYng0lFP_ELUlPmfdWd_CJZ6sVMOEDzfHj8tVyXirUfJGH7qF/w640-h570/Aggregata%20sinensis.png" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Top left: <i>Aggregata sinensis</i> oocysts in the membrane between the arms of an octopus. Top right: Oocysts in the branchial heart.<br />Bottom left: Sporocysts found within an oocyst. Bottom right: Sporozoite released from a sporocyst.<br />Photos from Fig. 1 and Fig. 2 of <a href=" https://link.springer.com/article/10.1007/s00436-021-07389-0">the paper</a>. <br /><br /></td></tr></tbody></table><div><a href="https://dailyparasite.blogspot.com/2010/09/september-30-aggregata-octopiana.html"><i>Aggregata</i></a> is a genus of apicomplexan which specifically targets cephalopods - mainly octopuses. Octopus can become infected from eating crustaceans such as shrimps which harbours the asexual stage of the parasite. Once they get into the octopus gut, the parasite takes over the digestive tract, and undergo sexual reproduction in the cells of the gut lining. There are <a href="https://www.marinespecies.org/aphia.php?p=taxdetails&id=391854">twenty different known species</a> of <i>Aggregata</i>, and it seems that for octopuses, there is no escape from this genus of parasite - even deep sea species living around hydrothermal vents are targeted by their own <a href="https://www.int-res.com/abstracts/dao/v91/n3/p237-242/">specialised species of <i>Aggregata</i> parasite</a>.</div><div><br /></div><div>So there are no doubt many other species of <i>Aggregata</i> out there which are still undiscovered. The paper featured in this blog post describes a species of <i>Aggregata</i> called <i>Aggregata sinensis</i> which has been found in octopus from the eastern-central coastal waters of China and the northern tip of Taiwan. The parasite was found infecting two species of octopus - the <a href="https://en.wikipedia.org/wiki/Amphioctopus_fangsiao">webfoot octopus</a> and the <a href=" https://en.wikipedia.org/wiki/Octopus_minor">long arm octopus</a> - both of which are commercially important species that are caught by the local fishermen. </div><div><br /></div><div>The parasite was rather common, and depending on the location, between 20-100% of the octopuses that the researchers examined were afflicted with <i>A. sinensis</i>. Because the way an octopus becomes infected is from eating parasitised prey, <i>Aggregata</i> infection initially starts in the digestive tract, but it doesn't stay there for long. In heavy infections, the parasite spills over into other parts of the body in a very visible way. As <i>Aggregata</i> proliferates in the octopus, it leaves tell-tale signs of their presence in the form of white cysts that speckle the octopus' body. Those white cysts are called <b>oocysts</b>, which are the results of the parasite's sexual reproduction. <i>Aggregata</i> can wreak a destructive toll on the octopus's health. As the parasite proliferates, they smother the gut lining and destroy the submucosa cells, which compromise the octopus' ability to absorb nutrients. </div><div><br /></div><div>As if that's not enough, those white oocysts are filled with microscopic spheres called <b>sporocysts</b> which need to depart from the octopus' body to continue the life cycle, and they do so in a destructive manner. The release of those <i>Aggregata</i> oocysts necessitates the rupture and shedding of the surrounding hosts cells, resulting in ulcers and atrophy of the gut lining and connective tissues. Once free in the surrounding waters, should the sporocysts find themselves in an unlucky crustacean, they unravel to reveal their payload of worms-shaped <b>sporozoites</b>. These squirm out and settle in the crustacean's gut where they undergo asexual reproduction, and start the life cycle anew.</div><div><br /></div><div>A recent study on the phylogeny of Apicomplexa suggests that <i>Aggregata</i> belongs to a group called the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7875001/">Marosporida</a> - which occupies a key evolutionary position within Apicomplexa, separate from the rest of the phylum. Which means that understanding parasites like <i>Aggregata</i> may also help us understand the evolution of the Apicomplexa phylum as a whole, and how they became one of the most successful and ubiquitous group of parasites on the planet.</div><div><br /></div><div>Reference:</div><div>Ren, J., & Zheng, X. (2022). <i>Aggregata sinensis</i> n. sp.(Apicomplexa: Aggregatidae), a new coccidian parasite from <i>Amphioctopus fangsiao</i> and <i>Octopus minor</i> (Mollusca: Octopodidae) in the Western Pacific Ocean. <i>Parasitology Research</i> <b>121</b>: 373-381.</div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0tag:blogger.com,1999:blog-6094038346173044955.post-8789400714134575742022-03-17T09:59:00.002-04:002022-03-17T10:04:19.494-04:00Thaumastognathia bicorniger<div style="text-align: left;"><a href=" https://www.jstage.jst.go.jp/article/pbr/2/1/2_1_1/_article">Gnathiidae</a> is a family of parasitic isopods that can be considered as ticks of the sea. I make that comparison not only because gnathiids are blood-feeding arthropods, but like ticks, their <a href="https://dailyparasite.blogspot.com/2014/12/gnathia-maxillaris.html">life cycle</a> involves going through a series of feeding and non-feeding stages. The blood-hungry fish-seeking stage is called a <b>zuphea</b> that, much like how a tick would on land, attaches itself onto passing fish and starts feeding to its heart's content. Once it is fully engorged with a belly full of blood, it becomes what's called a <b>pranzia</b>, which drops off the fish to grow and moult into its next stage. Gnathiid isopods need to go through alternating between the zuphea and the pranzia stage at least three consecutive times before they can reach full maturity.</div><div style="text-align: left;"><br /></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEgHfrT4GTl3t26mj9L_ype4q3GKSFiPhpOky0kFbkKsGuuySnCWTKBc1ABqWlJhD_0qiusp93S25bgnpV4dCHwXB-UXyVwqvkA9omykREeHaOdUvikCPvco1LKd0kKj26w0GFwt9oDFfgyjVxVMdw38w3LuWrlsmATeaAP6hDTwFdEe-r37KjPEC74o=s1508" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="821" data-original-width="1508" height="348" src="https://blogger.googleusercontent.com/img/a/AVvXsEgHfrT4GTl3t26mj9L_ype4q3GKSFiPhpOky0kFbkKsGuuySnCWTKBc1ABqWlJhD_0qiusp93S25bgnpV4dCHwXB-UXyVwqvkA9omykREeHaOdUvikCPvco1LKd0kKj26w0GFwt9oDFfgyjVxVMdw38w3LuWrlsmATeaAP6hDTwFdEe-r37KjPEC74o=w640-h348" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><i>Thaumastognathia bicorniger</i> stripe (left) and spots (centre) pigemented third stage pranzia, and adult male (right)<br />From Fig. 2. of <a href="https://bioone.org/journals/zoological-science/volume-39/issue-1/zs210057/First-Record-of-Elasmobranch-Hosts-for-the-Gnathiid-Isopod-Crustacean/10.2108/zs210057.short">the paper</a></td></tr></tbody></table><br /><div>The paper featured today is about <i>Thaumastognathia bicorniger</i>, a gnathiid isopod which has recently been described from the waters of Japan. The researchers who described this species found the isopod on various chimaera and sharks that were caught by fishing vessels operating in the waters of <a href="https://en.wikipedia.org/wiki/Suruga_Bay">Suruga Bay</a> and around <a href="https://en.wikipedia.org/wiki/Kumejima,_Okinawa">Kumejima Island</a>. Additionally, they were also able to obtain previously collected specimens of this isopod that had been stored at the laboratory of fish pathology at Nihon University. Those specimens were originally collected from various different cartilaginous fishes that were caught by fishing vessels off the southern coast of central Japan.</div><div><br /></div><div>Based on their samples, this isopod has been recorded to feast on the blood of at least ten different species of <a href=" https://en.wikipedia.org/wiki/Chondrichthyes">cartilaginous fishes</a> including nine species of sharks from six different families, along with one species of chimaera (also known as ratfish, in this case the <a href="https://en.wikipedia.org/wiki/Silver_chimaera">Silver Chimaera</a>). <i>Thaumastognathia bicorniger</i> larvae were always found in the gill chamber of their hosts, where they attached themselves to the blood-rich gill filaments. These isopods are tiny, with the third stage praniza larva measuring about 3.7-4.8 mm long, so having one or two of them would merely pose a minor inconvenience to the host. </div><div><br /></div><div>However, some sharks were found to be infected with dozens or even hundreds of those tiny blood-suckers. Of those, the <a href="https://en.wikipedia.org/wiki/Blotchy_swellshark">Blotchy Swellshark</a> (<i>Cephaloscyllium umbratile</i>), the <a href="https://en.wikipedia.org/wiki/Shortspine_spurdog">Shortspine Spurdog</a> (<i>Squalus mitsukurii</i>), and the <a href="https://en.wikipedia.org/wiki/Starspotted_smooth-hound">Starspotted smooth-hound</a> (<i>Mustelus manazo</i>) appeared to be among this gnathiid's favourite hosts, as they were commonly found to be infected with at least 50 <i>T. bicorniger</i> larvae and some even harboured hundreds of those blood-sucking isopods in their gill chambers. Additionally, much like how ticks are known to carry various pathogens, gnathiid isopods have also been implicated in the transmission of <a href=" https://www.sciencedirect.com/science/article/pii/S0020751913000027">blood-borne parasites</a> in coral reef fishes.</div><div><br /></div><div>The juvenile stages of <i>T. bicorniger</i> seem to come in two different colour patterns - spotty and stripey. This was only visible in the live or freshly caught specimens as the colour faded rapidly when they are preserved in ethanol. Genetic analysis revealed that despite their superficial differences, those two colour morphs belong to the same species, and it is unclear whether the different colour patterns signify anything, as they're not associated with a particular <a href="https://en.wikipedia.org/wiki/Haplotype">haplotype</a>, sex, nor host species.</div><div><br /></div><div>The researchers kept some of the gnathiid larvae alive in captivity to see if any of them would metamorphose into an adult stage - but only one successfully moulted into an adult male. Among gnathiid isopods, there is a high degree of sexual dimorphism - the male gnathiids have squat body with big mandibles, while in contrast, female gnathiid have a larger rotund body for brooding eggs into larvae. Neither of which look anything like a "typical" isopod like a <a href=" https://en.wikipedia.org/wiki/Woodlouse">woodlouse</a> or even the infamous tongue-biter parasite and its <a href="https://en.wikipedia.org/wiki/Cymothoidae">cymothoid</a> relatives.</div><div><br /></div><div>For other species of gnathiid isopods, metamorphosing from the third-stage pranzia into a mature adult is a relatively brief process. After their last feeding session, some species would take just a week or two to mature into a reproductive adult, while others may take up to two months at most. However, <i>T. bicorniger</i> took a whooping 204 days to moult from a third stage pranzia into an adult. So why does <i>T. bicorniger</i> take so long to mature compared with other species of gnathiid isopods?</div><div><br /></div><div>Gnathiid metabolism and growth is greatly affected by water temperature, and many of the gnathiids that have very short development time are found in warmer, tropical waters. In this study researchers kept their <i>T. bicorniger </i>at 10-20°C in their lab, which is slightly cooler than the water temperature that those other known gnathiids are regularly exposed to. However, there is a species of Antarctic gnathiid - <i>Gnathiia calva</i> - which <a href="https://www.researchgate.net/publication/226367453_Aspects_of_the_life-cycle_of_the_Antarctic_fish_parasite_Gnathia_calva_Vanhffen_Crustacea_Isopoda">only took 6 weeks</a> to transform into an adult despite living in waters that were kept at <b>0 to -1°C</b>.</div><div><br /></div><div>Alternatively it might have something to do with the fishes that they were feeding on. Many sharks have high levels of urea in their blood, which may make their blood more difficult to digest for any would-be blood-suckers. Lamprey that feed on basking sharks are specially adapted to <a href=" https://www.sciencedirect.com/science/article/pii/S109564330400162X">excrete large volumes of urea</a> which is found in their host's blood. The need to detoxify your food would most likely complicate the digestion process, decrease the blood's nutritional value, which would result in cost to development time. But then again there is another gnathiid species - <i><a href="https://link.springer.com/article/10.1007/s11230-008-9158-2">Gnathia trimaculata</a></i> - which infects <a href="https://en.wikipedia.org/wiki/Blacktip_reef_shark">Blacktip reef shark</a> (<i>Carcharinus melanopterus</i>) and it only takes 6 (for males) or 24 days (for female) to moult into an adult.</div><div><br /></div><div>So for now, the reason(s) why <i>T. bicorniger</i> seems to take such a long time to grow into an adult compared with other species of gnathiid isopods, remains a unsolved mystery.</div><div><br /></div><div>Reference:</div><div>Ota, Y., Kurashima, A., & Horie, T. (2022). First Record of Elasmobranch Hosts for the Gnathiid Isopod Crustacean Thaumastognathia: Description of <i>Thaumastognathia bicorniger </i>sp. nov. <i>Zoological Science</i>, <b>39</b>: 124-139</div>Tommy Leunghttp://www.blogger.com/profile/06421993204602775597noreply@blogger.com0