"So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite ’em; and so proceed ad infinitum."
- Jonathan Swift

October 31, 2010

October 31 - Desmodus rotundus

The common vampire bat, Desmodus rotundus, seemed like a good parasite to feature on Halloween. These mammals derive all of their nutrition from the blood of other mammals, usually cattle, but sometimes other livestock and even sleeping humans. They sneak up on their hosts using a very quiet hopping motion and then slice open the skin with razor-sharp teeth, lapping up the blood that spills out. Vampire bats can only survive a few days without feeding, but have evolved a social behavior known as reciprocal altruism where a bat that feeds successfully one night may regurgitate some of its meal to a hungry roostmate. Later, the recipient may be the lucky one and return the favor to this donor. Vampire bats can be found in many places throughout the neotropics, but have sometimes been subjects of eradication campaigns because of the fear of rabies that they can spread.

October 30, 2010

October 30 - Philophthalmus gralli

Continuing our theme of nasty places to have worms, how about under the eyelid?! Flukes of the genus Philophthalmus are found in the conjunctival sac of the eyes of many species of birds and rarely in humans. In this case, a rhea (Rhea americana) in a zoo had an unusually heavy infection of several hundred flukes in each eye. The intermediate hosts are aquatic snails. When the cercariae escape from the snail, they encyst on vegetation or occasionally at the surface of the water and the cysts are ingested by the final host, where they hatch and migrate to the eye.

Contributed by Mike Kinsella, photo by Melanie Church.

October 29, 2010

October 29 - Megalodiscus temperatus

Megalodiscus temperatus is a digenean trematode belonging to the order Echinostomatiformes (Family Diplodiscidae). Diplodiscid flukes have a pair of posterior diverticula in the oral sucker, and the posterior sucker of these trematodes is about as wide as the greatest width of the body. Megalodiscus temperatus are common parasites of the rectum and urinary bladder of frogs. Eggs are shed from frog hosts, and miracidia hatch soon after the eggs reach the water. There is only one intermediate host for M. temperatus, snails of the genus Helisoma. Snails become infected when penetrated with miracidia, releasing cercariae into the water that subsequently encyst in the skin of frogs. Frogs regularly molt the outer layers of their skin, often ingesting the sloughed skin and the encysted metaceriae. Metacercariae excyst in the rectum, maturing in one to four months. Tadpoles can also become infected when ingesting cercaria. In this case, M. temperatus encysts in the stomach and excysts in the rectum of the tadpole. During metaphorphosis (tadpole intestines shorten considerably), M. temperatus migrates anteriorly then posteriorly again to the rectum.

Contributed by Jessica Light.

October 28, 2010

October 28 - Hysteromorpha triloba

Hysteromorpha triloba , a strigeid trematode is a strange looking and generally small parasite found in the digestive tracts of fish-eating vertebrates. The first intermediate host is a snail (e.g., Gyraulus hirsutus), and the second intermediate hosts are fishes of the families Cyprinidae (Abramis sp., Hyborhynchus notatus, Idus idus, Leuciscus sp., and Tinca tinca), Poeciliidae (Poecilia vivipara), and Siluridae (Ameiurus sp.). In the fish intermediate hosts, metacercaria encyst in the musculature (forming white cysts) and the parasite is passed on to the definite host when infected fish are eaten. Definitive hosts include herons, egrets, pelicans, and cormorants.

Other images can be found here.

Contributed by Jessica Light.

October 27, 2010

October 27 - Brachylaima thompsoni

Brachylaima thompsoni is a digenean trematode (Family Panopistidae – previously Brachylaimidae) that parasitizes shrews in North America. Similar to other trematode species, B. thompsoni has a complex life cycle and it parasitizes two intermediate hosts before parasitizing its shrew definitive host. Both the first and second intermediates hosts of B. thompsoni are terrestrial gastropods. Documented first intermediate hosts include Agriolimax agrestis, Zonitoides arboreus, Deroceras leave, and Ventridens ligera (sporocysts of B. thompsoni are found in the digestive gland of the first intermediate host). Free-living cercariae then infest the second intermediate host (potential hosts include Neohelix albolabris and Webbhelix), where metacercariae develop in the pericardium or kidneys. Definitive hosts such as Short-tailed Shrews (Blarina brevicauda), Elliot’s Short-tailed Shrew (Blarina hylophaga), and Least Shrews (Cryptotis sp.) become infected when feeding on parasitized gastropods. B. thompsoni is commonly found in the large intestine of its definitive host and eggs of this tremaode are shed in the shrew fecal material. The first intermediate host becomes infected by ingesting the eggs, starting the cycle over.

Contributed by Jessica Light.

October 26, 2010

October 26 - Echinorhynchus salmonis

Echinorhynchus species are acanthocephalan parasites belonging to the family Echinorhynchidae. Like other acanthocephalans we’ve already seen (e.g. Neoechinorhynchus emyditoides; Moniliformis moniliformis; Pseudocorynosoma constrictum, these thorny headed worms parasitize the intestines of fish and amphibians. The species shown here is probably Echinorhnychus salmonis, an acanthocephalan with a Holarctic distribution, occurring in fresh and brackish waters and commonly parasitizing salmoniform and other fishes (intermediate hosts include amphipods such as Monoporeia affinis). Echinorhynchus are often the topic of research projects including effects on host feeding ecology, anti-predator behavior, and host spawning. Here are two links about Echinorhynchus species:
First Site
Second Site

Contributed by Jessica Light.

October 25, 2010

October 25 - Aspidogaster conchicola

Aspidogaster conchicola is a trematode (Trematoda: Aspidogastrea) with a direct life cycle. Hosts include freshwater clams and snails (e.g., Viviparus species and Goniobasis livescens) and this particular one was found in Douglas Lake, Michigan, parasitizing a mussel belonging to the genus Ligumia. Hosts become infected when ingesting eggs of A. conchicola and adult worms can commonly be found in the mantle, pericardial, and renal cavities of their hosts. If parasite densities are high, A. conchicola may have negative consequences on host fitness. A. conchicola is the type species of the genus, and recently phylogenetic studies have found that A. conchicola is closely related to Lobatosoma species, resulting in a non-monophyletic Aspidogaster.

Contributed by Jessica Light.

October 24, 2010

October 24 - Lathraea clandestina

Today we have a pretty parasite - Lathraea clandestina, or the Purple Toothwort, is a parasitic plant that uses willows, poplars and alders as its hosts. Its name comes from the fact that its remnant, below-ground and chlorophyll-less leaves resemble teeth. These plants produce quite large fruits for their size, which burst when ripe, sending their tiny seeds off to be carried by rain or other moisture to new hosts. L. clandestina is found throughout Western and Central Europe and seemingly were recently introduced into the U.K. and Ireland.

October 23, 2010

October 23 - Trombidium holosericeum

The animal in the photo is not a parasite - but its offspring are. Like Eutrombicula alfreduggesi, Trombidium holosericeum is a mite that has parasitic larvae and nymphs. The larvae, commonly known as chiggers, can cause real distress to their hosts - including humans - as they feed. They do not crawl under the skin, nor do they feed on blood - what they do is attach themselves to the skin, pierce it. and inject enzymes that can break down the tissue. A hollow tube known as a stylosome forms - the chiggers will continue to "spit" in these enzymes and then suck up the nutrients. After about 3 to 5 days, they will drop off the host and transform into nymphs. They find a new host, feed in a similar way, and then drop off to molt into adults. The adults are not parasitic, but rather feed on plant juices or are predatory to other small arthropods.

October 22, 2010

October 22 - Lophoura brevicollum

Lophoura brevicollum is a parasitic copepod that infects the smooth grenadier Nezumia liolepis, a deep sea fish that is found in the bathypelagic depths, about 1200 metres (about three-quarters of a mile) down off the coast of Sinaloa, Mexico. The anterior of the parasite forms an anchor-like holdfast that is embedded in the back of its fish host. One of the more unusual morphological features of this parasite is a pair of peculiar tassels protruding from the abdomen, just in front of its elongated egg sacs. The function of these tassels is possibly related to the habitat of its host. Because L. brevicollum is an ectoparasite, it is exposed to the same environmental conditions as its fish host. In this case, it is the cold, dark surroundings of the deep sea. It has been suggested that the exotic brush-like protrusions of the copepod are adaptations to limited oxygen availability. The protrusions increase the copepod's body surface area to enhance oxygen uptake in the oxygen-poor environment of the bathyal zone.

Gomez, S., Deets, G.B., Kalman, J.E., Morales-Serna, F.N. (2010) Lophoura brevicollum n. sp. (Copepoda: Siphonostomatoida: Sphyriidae), a parasite of the smooth grenadier Nezumia liolepis (Gilbert, 1890) (Pisces: Macrouridae) from the Eastern Pacific, and a new record and new host of Lophoura unilobulata Castro R. and Gonzalez. Journal of Crustacean Biology 30(1): 129-140.

Contributed by Tommy Leung.

October 21, 2010

October 21 - Clinostomum marginatum

On the list of unpleasant places to have a worm infection, in one's mouth would have to be near the top. Flukes of the genus Clinostomum live in the mouth of aquatic birds, especially herons and egrets. The infective metacercariae of these flukes are found just under the skin or in the muscles of many species of freshwater fish, where they are known as “yellow grubs.” For photos of the grubs, see this site. Although cooking kills the parasites, eating a fish with an infection like this is easier said than done and many infected fish are discarded by fishermen.

Contributed by Mike Kinsella.

October 20, 2010

October 20 - Urastoma cyprinae

Yesterday you met a copepod that lives in the mantle of bivalves. Today, meet a turbellarian (a platyhelminth) that could be cozying up to those crustaceans. Urastoma cyprinae spends the majority of its life in the gills of bivalves, specifically mussels such as the gastronomically and thus economically important species Mytilus edulis, Mytilus galloprovincialis, and Crassostrea virginica. They live and feed and grow in the mussels, but their complete life cycle stumped researchers because eggs were never observed in these hosts. Researchers in Spain recently discovered that when U. cyprinae is ready to lay eggs, it leaves the bivalve, secretes a protective cocoon around itself and produces an egg sac. About 24 days later, the young hatch out (shown in the photo), make their way out of the coocoon and swim off to find new mussel hosts. The adults sometimes appear to just die in the cocoons, but sometimes also were observed to escape from it themselves and head off to lay more eggs.

Read more about these parasites here and here.

Photo by Celia Crespo González.

October 19, 2010

October 19 - Pseudomyicola spinosus

Pseudomyicola spinosus is a parasitic copepod that is found in more than 50 species of bivalves around the world, ranging from clams to mussels to scallops. It dwells in the mantle cavity of the bivalve, where it grazes on mucus produced by the host. This copepod has a pair of hook-like attachment appendages that allow it to cling to the host tissue and avoid being swept away by the constant water flow that passes through the mantle cavity. In large numbers, they can cause considerable tissue damage to the host - the constant attachment and reattachment of the copepod (which can be highly mobile within the host's body cavity) aggravate host tissue, causing epithelial erosion and induce over-production of mucus. At lower infection levels, the tissue damage caused by the copepod is almost negligible, but it does have a more subtle effect on its host. It has been found that infection with just a few P. spinosus is associated with higher levels of infections by metcercarial cysts of echinostomatid trematodes such as Curtuteria australis and Acanthoparyphium. Once again, this is possibly due to the effects of the copepod's attachment appendages, which damage the epidermis in such a way that facilitates subsequent invasion by trematode cercariae.


Cáceres-Martínez, J. and Vásquez-Yeomans, R. (1997). Presence and histopathological effects of the copepod Pseudomyicola spinosus in Mytilus galloprovincialis and Mytilus californianus. Journal of Invertebrate Pathology 70, 150–155.

Leung, T. L. F. and Poulin, R. (2007). Interactions between parasites of the cockle Austrovenus stutchburyi: Hitch-hikers, resident-cleaners, and habitat-facilitators. Parasitology 134, 247–255.

Post and image by Tommy Leung.

October 18, 2010

October 18 - Necator americanus

Necator americanus is a species of nematode commonly known as a hookworm. It has a very broad distribution and has long been common in the Southeastern U.S. The eggs are shed in the host's feces and then they go through several larval stages in the soil. Eventually they develop into filariform larvae, which find a host, often a barefoot kid, and burrow in through the skin in their feet. They will make their way into blood vessels, and eventually find their way to the lungs. They get coughed up, swallowed, and then mature into adults in the GI tract. They use their rather fearsome jaws to latch onto a villus in the small intestine, where they ingest the host's blood. The symptoms can be mild anemia, diarrhea, and cramping but infection can also lead to more serious things such as iron-deficiency and even developmental problems. Sounds pretty awful, right? Yet, believe it or not, many people are now becoming infected with these parasites - on purpose. The reason is that recently it was observed that people in developing countries, where hookworm and other parasites are prevalent, do not very often have auto-immune diseases like allergies, asthma, etc. and it was hypothesized that our hyper-sterile Western lifestyle that has led to "bored" immune systems that turn on our own bodies. Helminthic therapy is a new movement whereby people purposefully expose themselves to worms such as hookworm in an effort to keep their immune system busy attacking the parasite so that it doesn't cause these other problems. A documentary about this new therapy has been made - you can learn more about it here.

October 17, 2010

October 17 - Brachylecithum mosquensis

Host specificity in trematode parasites ranges from strict specificity, in which a species of trematode infects only one species of host, to moderate specificity, in which a species may infect a range of closely related host species, all the way to low specificity, in which a trematode may infect different orders of hosts (e.g. herons and pelicans) or even different classes of hosts (e.g. birds and mammals). Proof of specificity in the past relied on experimental infections of hosts. But recently, DNA technology has allowed us to prove that trematodes from different hosts are genetically identical. Brachylecithum mosquensis, a common liver fluke of American robins, was recently matched to liver flukes from a vagrant shrew, Sorex vagrans, from Montana. The common link between these dissimilar hosts is a fondness for snacking on carpenter ants.

See more here: Kinsella, J. M., and V. V. Tkach. 2009. Molecular identification of an avian dicrocoeliid, Brachylecithum mosquensis, in a vagrant shrew, Sorex vagrans, from Montana. Comparative Parasitology 76:287-289.

Image and post by Mike Kinsella.

October 16, 2010

October 16 - Cochliomyia hominivorax

The New World screwworm, Cochliomyia hominivorax, is a parasitic dipteran whose maggot larvae invade organs or tissues of living organisms in a type of infestation called myiasis. Attracted to wounds and sores, an adult C. hominivorax female deposits batches of 10 to 400 eggs onto the living tissue of warm-blooded vertebrates, even humans. Larvae feed and develop for 3 or 4 days and then drop off the host body to pupate in the soil, later becoming adult flies. Once prevalent throughout North America, this parasite was known for infesting livestock and causing major economic loss. Their damaging impact prompted the development of the Sterile Insect Technique (SIT) by Raymond Bushland and Edward Knipling in the 1950s. Male screwworm flies were sterilized by irradiation in the laboratory and released to mate with wild females. The females subsequently produced infertile eggs and over generations of sterile male release the population of C. hominivorax was greatly reduced. This control method was successful in eradicating the parasite from North America and much of Central America, leading former U.S. Secretary of Agriculture Orville Freeman to refer to the Sterile Insect Technique as "the greatest entomological achievement of [the 20th] century."

Contributed by Phil Scheibel.

October 15, 2010

October 15 - Nerocila acuminata

Nerocila acuminata is a parasitic isopod related to Cymothoa exigua, the infamous "tongue-replacer". While N. acuminata doesn't have the morbid habit of replacing the tongue of its host with itself, that certainly doesn't make it more endearing. This isopod clings onto the skin of its fish host, feeding on blood and tissue. When it detects a potential host, this parasites becomes a fish-seeking missile - it launches itself at the target fish like a guided torpedo, making precise directional and speed adjustments to ensure it lands on its target with claws outstretched . Upon contact, the isopod starts digging in, causing terrible, terrible damage to the skin of its fish. In addition to damaged tissue and blood loss, such aggravated injuries can often lead to secondary infection by bacterial infection. Compared with the "tongue-biter", this parasite is one nasty customer.

Contributed by Tommy Leung and photo by Peter Bryant.

October 14, 2010

October 14 - Lepeophtheirus pectoralis

Lepeophtheirus pectoralis (Müller, 1776) is a caligid copepod usually found on the body surface of the European flounder, Platichthys flesus (Linnaeus, 1758) (Teleostei: Pleuronectidae). Its relatively large body size makes it easily recognizable to any observer. As any other caligid, the parasite has the ability to move freely over the body surface of its host. Notwithstanding, it is remarkable in presenting a well-defined spatial distribution pattern on the host’s body, with the gravid females accumulating, mainly, in the inner surfaces of the pectoral fins. Indeed, this behavioral feature was in the origin of the species name. The records in the literature suggest that the parasite tends to occur with considerably regularity and high numbers on its host.

For details on the species ecology, see the papers below:
Cavaleiro, F. I. & Santos, M. J. (2007) Survey of the metazoan ectoparasites of the European flounder Platichthys flesus (Linnaeus, 1758) along the north-central Portuguese coast. Journal of Parasitology 93, 1218-1222.
Cavaleiro, F. I. & Santos, M. J. (2009) Seasonality of metazoan ectoparasites in marine European flounder Platichthys flesus (Teleostei: Pleuronectidae). Parasitology 136, 855-865.

Contributed by Francisca I. Cavaleiro & Maria J. Santos, Universidade do Porto, Faculdade de Ciências, Departamento de Biologia, Rua do Campo Alegre, s/n, FC4, 4169-007 Porto, Portugal.

October 13, 2010

October 13 - Nanophyetus salminicola

West of the Cascade Range in the Pacific Northwest, it is an extremely poor idea to feed fish scraps to your dog. This tiny intestinal fluke is the reason. The parasite itself is relatively harmless but it can act as a vector for a rickettsial illness caused by Neorickettsia helminthoeca (“helminth,” as we all should know by now, is Greek for “worm”). When a canid is infected by eating uncooked salmon, the rickettsia can cause symptoms such as vomiting, diarrhea, and dehydration, which can be fatal in as many as 90% of cases if untreated. For unknown reasons, cats, raccoons and bears are not susceptible to the illness.

Contributed by Mike Kinsella.

October 12, 2010

October 12 - Acanthocheilus rotundatus

My what big teeth you have! That might be scarier if they weren't on a stomach nematode, but rather the creature that it lives inside. Acanthocheilus rotundatus parasitizes several species of hound sharks (e.g. Galeorhinus galeus, Mustelus griseus). This species was described way back in 1819 and has been found from the Adriatic Sea to the Pacific.

The image is adapted from this paper.

October 11, 2010

October 11 - Treponema pallidum

On Columbus Day, it seemed appropriate to feature Treponema pallidum, the bacterium that causes syphilis and other diseases such as bejel and yaws. Why? Because Columbus had syphilis? No...at least not that I know of. The reason stems from another book by Robert Desowitz called "Who Gave Pinta to the Santa Maria?" In this book, Desowitz ponders the exchange of diseases between the Old World and the New World when exploration and colonization by Europeans began. One of these potential continent swaps was Treponema pallidum. Some contend that Europeans brought the bacteria to the New World where it infected people there and mutated to cause not syphilis, but pinta, which is more of a skin affliction. Others argue the opposite- that the voyages to the Americas resulted in the introduction of T. pallidum to Europe, where, because of the colder climate inspiring people to wear more clothing, the bacteria became spread via sexual contact instead. The bacteria found in each of the diseases are almost identical in morphology, serology and even genetically, so it's still somewhat of an open question as to why they sometimes produce one pathology instead of another. Currently, though, most agree that the bacterium that causes pinta is a different species, now known as Treponema carateum, with the others classified as subspecies of T. pallidum.

October 10, 2010

October 10 - Microdajus langi

The parasite for today comes from a strange family of ectoparasitic crustaceans called Tantulocarida. There are only a few species within this family and they have a very peculiar development. They are parasitic on a number of deep sea crustaceans, and Microdajus langi itself infects small, shrimp-like crustaceans call tanaids.

Tantulocarids have a very strange life-cycle which is either asexual (which is more common) or sexual (relatively rare). In the asexual cycle, only females larvae are produced. Non-feeding larval stages known as tantulus are released from asexual females which resemble sacs and these larvae can directly attach and infect another host. On the left side of the accompanying photo is an immature female that had just attached onto the host, but once it is attached, it undergoes a strange transformation. On the right side of the photo, you can see a female that has just begun undergoing this development and she eventually develops into a bloated sac filled with eggs.

However, in the sexual cycle both males and females are produced and while males have never been observed alive, they have well-developed swimming legs and sensory organs which allow them to actively seek out and inseminate females. Once fertilised, the female attaches herself onto a crustacean host to start the cycle anew.

Photos from: Boxshall, G.A. and Lincoln, R.J. (1987) The Life Cycle of the Tantulocarida (Crustacea). Philosophical Transactions of the Royal Society of London. Series B 315: 267-303.

Contributed by Tommy Leung.

October 9, 2010

October 9 - Haemoproteus columbae

Lots of people are a little grossed out by pigeons, jokingly (?) calling them "flying rats". They'd probably be even more grossed out to know that many of those pigeons are hosts to a malaria-like blood parasite called Haemoproteus columbae. These parasites produce large kidney-shaped gametocytes in the red blood cells of doves and pigeons. These infected erythrocytes are ingested by hippoboscid flies (see this post for a similar species) that scamper through the feathers of the birds and feed on their blood for nourishment. H. columbae is the type species for its genus, which was for many years considered to be a large group of morphologically similar parasites that infected not just doves, but other birds, turtles and lizards as well. Molecular data have recently shown, though, that the forms in doves are a distinct lineage, not closely related to the others. This thus also corresponds to the vectors that are used as the parasites in other birds are transmitted by midges, not hippoboscids.

Photo by Jessi Waite.

October 8, 2010

October 8 - Plasmodium relictum

The beautiful birds of Hawai'i have been battling with an invasive malaria parasite known as Plasmodium relictum, and several - perhaps 10 or more - species have been lost to extinction, due, in part to this novel pathogen. In the early 1800's, the mosquito, Culex quinquefasciatus was brought to Hawai'i, and this vector allowed the parasite to take hold on the islands as well. Because the mosquito does not go much above 4000 meters in elevation, many native lowland species have pushed their ranges up in altitude, but since most of the islands are lower than 5,000 meters, there's just not very far to go. P. relictum has an incredibly wide geographic range and infects a large number of bird species, making it an unusual generalist amongst its kin.

The image is from the USGS Microbiology Image Gallery and was taken by Carter Atkinson.

October 7, 2010

October 7 - Leucocytozoon simondi

Leucocytozoon simondi is a blood parasite that is common in ducks and other waterfowl in the northern U.S. and Canada. These parasites, part of the same order of parasites as those that cause malaria in humans (Haemosporidia), are transmitted from duck to duck via the bites of blackflies. Their asexual replication occurs in the livers of the birds, followed by appearance of the transmission stages or gametocytes in the blood cells. Because of their large size, deep staining, and propensity to push the nucleus of the red blood cell way up against the cell membrane, these parasites were originally thought to infect white blood cells, not red ones. This species is happy to infect both wild and domestic hosts, but in the latter, they can actually kill the birds through liver damage and anemia.

October 6, 2010

October 6 - Hymenolepis nana

Hymenolepis nana, or the dwarf tapeworm (only 40 mm long!), is thought to be the most common human cestode on the planet. Unusual amongst tapeworms, H. nana does not require an intermediate host, but can be passed simply from one person (or rodent) to another via the ingestion of eggs that are shed in the feces, and auto-infection occurs in parts of the world where the worms are common. This direct life cycle is thought to be a recent adaptation in this species as the life cycle can be completed via an intermediate such as a flour beetle, much like its cousin, H. microstoma that you met way in the beginning of the year.

Image from the CDC Public Health Image Library.

October 5, 2010

October 5 - Petromyzon marinus

The sea lamprey, Petromyzon marinus, is a rather gruesome fish - almost right out of a science fiction movie. Hatched in freshwater rivers, the larvae do not possess these fearsome mouths, but are toothless and live a quiet life, buried in the mud where they simply filter feed. Once they grow to a larger size, however, they metamorphosize into the adult, parasitic form, migrate to the sea, and use their suction-cup shaped mouth to latch onto a fish such as a salmon or other bony fish. There, firmly attached, the razor-like teeth and tongue rasp away at the host's flesh and allow the lamprey to feed on blood and bits of tissue. Host fish often die from the excessive blood loss or infections that ensue in the wounds made by these parasites, which can grow up to three feet in length. Native to the coasts of North America and Europe as well as Lake Champlain, which separates New York from Vermont, the construction of the St. Lawrence Seaway may have allowed these parasites to take up firm residence in the Great Lakes, where they now are considered pests due to their feeding on popular game fish such as lake trout and their disruption of the native ecosystem.

October 4, 2010

October 4 -Gynaecotyla longiintestinata

Gynaecotyla longiintestinata is a marine trematode from the Aveiro estuary of Potugal. It is in the same family as Maritrema novaezealandensis- the Microphallidae. G. longiintestinata has a typical life-cycle for a trematode from the microphallid family - its uses a snail, in this case the intertidal whelk, Nassarius reticulatus, as a first intermediate host. From there, free-swimming larval stages called cercariae are produced and released into the environment, where they infect the second intermediate host, in this case the crab, Carcinus maenas. They occupy a very specific and peculiar microhabitat within the crab, namely its antennal glands. The definitive hosts of this parasite are shorebirds that feed on crabs.

Photo from:
Russell-Pinto, F. and Bartoli, P. (2002) Cercaria sevillana n. sp., a new cercaria (Digenea: Microphallidae) from Nassarius reticulatus (L.) (Mollusca: Prosobranchia) in Portugal. Systematic Parasitology 53: 175-182.

Contributed by Tommy Leung.

October 3, 2010

October 3 - Toxocara canis

Toxocara canis is a roundworm (nematode) that occurs worldwide in dogs. In adults, they are generally asymptomatic, but they can be fatal to puppies, particularly if the infection is heavy. Transmission usually occurs via ingestion of the eggs, which are passed in feces. Once swallowed, the larvae hatch and embark on a scenic route - from the intestine to the liver and lungs via the blood stream, where they are coughed up, swallowed again, and eventually mature. Other hosts, including human pet-lovers, can become infected and that characteristic larval wandering can make those humans very sick themselves.

October 2, 2010

October 2 - Peachia parasitica

Peachia is a genus of anemones, but very different from the big gentle waving sort you see on coral reefs, with happy families of Nemo-like anemone fishes frolicking in them. No, Peachia is a parasite, one of very few parasitic anemones. Who falls victim to a parasitic anemone? Another cnidarian: the jellyfish, Cyanea capillata. I’ve seen them in sea nettles (Chrysaora sp.), too. The few publications of Peachia suggest that it may be a facultative parasite; McDermott et al describe one that lived for 4 years in the lab. Peachia is just another fine example showing how many times parasitism has arisen in the evolutionary history of life on this planet.

McDermott, J.J. et al. (1982) The occurrence of the anemone Peachia parasitica as a symbiont in the scyphozoan Cyanea capillata in the lower Chesapeake Bay. Estuaries 5(4):319-321.

Contributed by Al Dove.

October 1, 2010

October 1 - Placobdella papillifera

Closely related to a glossiphoniid leech we saw earlier, Placobdella papillifera is a pretty leech distributed in North American freshwater habitats. P. papillifera is a blood-feeder, feeding on turtles (and sometimes alligators!). This leech was found under a rock in Savannah River in South Carolina. There are two pictures shown here, one showing the papillae on the dorsal surface and one showing the smooth ventral region. This leech was large, filling out the entire bottom of a petri dish! (Click on the thumbnail to get a good look at its pretty papillae.)

Contributed by Jessica Light.