"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

September 30, 2010

September 30 - Aggregata octopiana

This year, a particular octopus named Paul achieved fame and stardom due to some of his famous shenanigans relating to the World Cup. However, even an invertebrate celebrity such as Paul is not without a parasitic nemesis. Aggregata octopiana is a species of single-celled parasite that infects the common octopus, forming cysts in various parts of the body including the gills, digestive tract, and epidermis. The details of the parasite's life-cycle are currently not clear, though it is known to be a two-host life-cycle involving alternating phases of sexual and asexual reproduction. The sexual phase of this parasite occurs within the octopus where it undergoes a series of differentiation and cell divisions to produce produce infective stages that are shed into the environment. The parasite then infects prawns or other crustaceans that act as the intermediate hosts where asexual phase occurs. The life-cycle starts anew when the infected crustacean is eaten by an octopus.

Contributed by Tommy Leung.

September 29, 2010

September 29 - Tunga penetrans

Tunga penetrans is a species of flea found in Central and South American and the Caribbean that has a similar life cycle to other fleas, such as Ctenocephalides felis, with one major exception. The females on T. penetrans are not content to hop onto a mammal, drink up some blood and move on - no, instead they move in. Commonly known as chigoe fleas (not to be confused with chiggers, which are larval mites), T. penetrans burrows headfirst into the skin, producing a lesion that is almost always on the foot and is extremely itchy and irritating. The lesion will have a black center, which are the two hindmost legs of the flea and her abdomen. After she feeds on blood from the epidermal capillaries, she will swell up like a little balloon and begin to pump eggs out when her host is walking on sandy soil. In this photo, you can see the familiar head of the flea, but her swollen abdomen has been damaged during the removal from the infected person. A large egg is visible, however.

Image is from the CDC Public Health Image Library.

September 28, 2010

September 28 - Aphanomyces invadans

Aphanomyces invadans is a highly pathogenic oomycete fungi which infects the Atlantic menhaden Brevoortia tyrannus and many other species of fish from around the world. This water mould has been implicated in massive fish kills in North Carolina, resulting in hundreds of thousands of dead fish. On average, an infection resulting from less than 10 zoospores (the infective stage of this fungi) is enough to kill a fish, and even infection by just a single zoospore can result in ulcerous lesions that can lead to mortality. Fish infected with the fungi develops ulcerous lesions which ultimately lead to extensive tissue necrosis. This fungus develops extremely quicky, doubling its hyphal mass every ten days, and it is also highly invasive, extending its hyphae into various tissues including the liver, kidneys and spinal cord of the fish host. Interestingly, A. invadans outbreaks are associated with high rainfall. This is likely due to the fact that this water mould has a low salinity tolerance and will not grow in higher salinity waters.

Kiryu et al. (2003) Infectivity and pathogenicity of the oomycete Aphanomyces invadans in Atlantic menhaden Brevoortia tryannus. Diseases of Aquatic Organisms 54: 135-146.

(Photo from this paper.)

Contributed by Tommy Leung.

September 27, 2010

September 27 - Odhnerium sp.

Digeneans are flatworms famous for their plastic morphology, that is, the flexibility expressed in their body plan; the variations-on-a-theme, if you will. There are few better examples than Odhnerium species, a genus of accacoeliid worms parasitic in the intestine of the ocean sunfish, Mola mola. Most digeneans have either 0, 1 or 2 suckers, with 2 being the overwhelmingly most common body plan: an oral and a ventral sucker. Then along comes Odhnerium, which lines the anterior dorsal surface with muscular pseudosuckers, in this case at least 9 (they show up as blue waves). What’s a pseudosucker? Good question! It turns out that suckers have a very specific definition: a capsule-bound muscular attachment organ that works by suction. In this case, the suckers are apparently not capsule-bound (i.e. there’s no connective tissue membrane around them) so they only look like suckers – hence “pseudosuckers”. Still, it’s a pretty crazy departure from the normal body plan for digeneans, and it’s hard not to wonder what they’re so important for, since tens of thousands of gut dwelling fluke species do just fine without them. And while we’re at it, check out the ventral sucker, which is up on a sort of stalk called a pedicel, and is more like a pair of muscular flaps forming a clamp, than a typical round sucker.

The blue appearance of the suckers in this particular photo is a trick of the light. The photo was taken during processing to make the specimen into a permanent wholemount. There’s a step in the process when the worm has had all its water replaced by ethanol, and then you gradually replace the ethanol with a clearing agent like eugenol or (in this case) methyl salicylate. As the met-sal penetrated and cleared the tissues, this handsome colour was created for a few seconds, and I snapped the pics because it looked cool.

Contributed by Al Dove.

September 26, 2010

September 26 - Carnus hemapterus

Carnus hemapterus is a species of fly where the adults (the imagines, plural of imago), feed on the blood of nestling birds, particularly those of large birds such as owls or falcons. Larvae are birthed by females and feed just on the detritus in the nest, but then the development and emergence of the imagines coincides with the hatching of the birds. Both winged and unwinged flies may be present.

September 25, 2010

September 25 - Isospora felis

Isospora felis is a coccidian parasite of cats that typically has a direct life cycle, but may also pass through small rodents , which can act as vectors for these parasites. They infect the cells of the small intestine and can produce GI distress in their feline hosts. This genus is quite large, but not much work, particularly molecular work has been done on the group, to tease apart which hosts might be paratenic and which species might be cryptic.

Image by Steve Upton.

September 24, 2010

September 24 - Acanthochondria cornuta

Acanthochondria cornuta (Müller, 1776) is a chondracanthid copepod that infects the European flounder, Platichthys flesus (Linnaeus, 1758) (Teleostei: Pleuronectidae), in different geographic locations, including, the coast of Portugal. It is a site-specific marine ectoparasite that occurs generally with regularity and in high numbers in the branchial chambers of its flatfish host. As in all other species of chondracanthids, the male is dwarf, being usually found attached to the female in the vicinity of the genital region. In other words, he is not found directly attached to the fish host and is called a “hyperparasite”.

See these papers:
1. 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.
2. 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.

September 23, 2010

September 23 - Diphyllobothrium latum

A common item in Jewish cuisine is gefilte fish, small boiled balls of minced fish meat. Unfortunately, though, the preparation of these little treats typically involved testing the gefilte fish as it cooked, meaning early tastes were of undercooked fish. That habit resulted in lots of Jewish grandmothers becoming infected with a tapeworm called Diphyllobothrium latum. Native to Scandanavia and eastern Russia, these parasites were brought to the U.S. with immigrants who settled in Minnesota, Wisconsin and other northern climes all the way to the Pacific Northwest states and the worms easily adapted to the ecosystem there, infecting native fishes. The life cycle is complex and can involve numerous hosts, beginning with copepods that ingest the eggs and then moving up the food chain to larger and larger fish until they are consumed by a person. Many people do not realize that they are infected as the symptoms may, in fact be mild, even though the tapeworms can be more than 10 meters (i.e. more than 30 feet!) long and pump out a million eggs a day. A common one is a severe vitamin B12 deficiency, however. There are two important components to stopping the spread of this parasite: refraining from defecating in lakes and freezing fish before consuming and cooking it properly. These parasites have likely been associated with humans for a very long time - evidence of these worms has been found in settlements along the coast of South America that may be as old as 10,000 years.

Image from the CDC Public Health Image Library.

Read more about this parasite in Robert Desowitz's wonderful book, "New Guinea Tapeworms and Jewish Grandmothers".

September 22, 2010

September 22 - Ambylomma americanum

Yeeee haw! Today's parasite is the Lone Star Tick, Ambylomma americanum, though I must confess that although it is sometimes found in Texas, its name comes from the spot on the back of the females of the species. These ticks primarily feed on cattle or deer as adults. This species of tick is not thought to vector Lyme Disease, but they do transmit other parasites to humans, such as granulocytic ehrlichiosis (Ehrlichia ewingii), tularemia (Francisella tularensis), and a close relative of the Lyme disease bacterium, Borrelia lonestari, which produces Southern tick-associated rash illness (STARI). A. americanum also holds the distinction of being the first species of tick that was described from the United States - back before we were the United States - in 1754.

September 21, 2010

September 21 - Apodinium floodi

Most dinoflagellates are photosynthetic plankton that form the basis of many aquatic food webs or mutualist symbionts, sharing and sharing alike with their hosts. Apodinium floodi is an exception. Unlike its photosynthetic cousins, it is an ectoparasite, and its host is the pelagic sea squirt Oikopleura labradoriensis. Sea squirts, despite their sac-like appearance, actually belongs to a group of animals call the urochordates, which are more closely related to vertebrate animals than all other invertebrates. Apodinium floodi uses a structure call a peduncle to attach itself to the tail of the sea squirt, and penetrate the host's notochord to absorb nutrients from its blood.

It is an evolutionary marvel - a single-celled algae which has evolved to make a living by sucking blood from a pelagic animal!

Contributed by Tommy Leung.

September 20, 2010

September 20 - Neospora caninum

Originally confused with Toxoplasma gondii, Neospora caninum is a coccidian parasite that alternates between cattle hosts where it forms cysts in their tissues and canines such as dogs and coyotes, though transplacental transmission has been demonstrated in both intermediate and determinant hosts. Although this parasite does not seem to infect humans, it is of interest because it can cause spontaneous abortions in livestock if they are infected (resulting in economic losses perhaps as much as $24 million in Texas alone) and has also been linked to neurological disorders in dogs. The parasite is found virtually everywhere in the world where there are canines and cattle.

Photo of N. caninum in calf brain by Steve Upton.

September 19, 2010

September 19 - Phasmarhabditis hermaphrodita

Parasites have to find their hosts and if you're a parasite of gastropods like snails and slugs, that means being attracted to slug slime - i.e. the chemicals found in the mucus secreted by slugs and snails. Phasmarhabditis hermaphrodita is a parasitic nematode that infects and kills its molluscan hosts and has, in fact, been shown to be attracted to their mucus. These parasites are commercially sold as slug pest control agents in the U.K. Other studies have shown that the parasites are somehow able to manipulate the behavior of their hosts to crawl into the soil -this allows the nematodes to complete their development before the dead slug or snail or consumed by a scavenger.

Image is from this site.

September 18, 2010

September 18 - Coitocaecum parvum

One of the problems of being a parasite with a complex life-cycle is the need to have all the appropriate hosts in the environment - the absence of any one of these hosts can mean a break in the chain, which spells doom for the continuation of the parasite's lineage. However, some parasites have evolved ways around that particular problem.

Coitocaecum parvum is a trematode found in New Zealand. Like most trematodes, it has a three host life-cycle, with amphipods (a kind of small crustacean) serving as a second intermediate host. Usually, in order for the parasite to complete its life-cycle and reach sexual maturity, the amphipod host needs to be eaten by the parasite's definitive host, a small freshwater fish call the common bully (Gobiomorphus cotidianus). However, in situations where the fish is absent, the parasite has another trick up its sleev...err, ventral sucker... Instead of waiting for a fish to come along (which might not happen before its short-lived crustacean host dies), it switches up its game - it becomes "progenetic" and reach sexual maturity within the amphipod itself. Because it is a hermaphrodite, it can simply fertilise its own eggs, which will be released into the environment when the amphipod dies and decompose.

The photo shows a pair of progenetic C. parvum (one still in its cyst, the other released from its cyst and surrounded by its own eggs) next to a pair of non-progenetic C. parvum.

Lagrue, C., and R. Poulin. 2007. Life cycle abbreviation in the trematode Coitocaecum parvum: can parasites adjust to variable conditions? Journal of Evolutionary Biology 20: 1189-1195.

Contributed by Tommy Leung.

September 17, 2010

September 17 - Travassostrongylus sp.

New World opossums are infected by a variety of parasites, including intestinal nematodes from the genus Travassostrongylus. Travassostrongylus encompasses 10 known species and is included in the richest superfamily of parasitic nematodes, Trichostrongyloidea. Using pointed ridges that run along their body, these worms constrict around microvilli in the walls of the intestine and feed on blood. The arrangement of the ridges aids in classification, as do the finger-like structures on the male copulatory bursa, which is a lobular tail that embraces the female during copulation. Species in the genus Travassostrongylus are found in Central and South American opossums. From the semi-aquatic marsupial Chironectes minimus, to the arboreal mouse opossum Marmosa, to the generalist Didelphis, this parasite infects a diverse group of mammals.

Contributed by Phil Scheibel.

September 16, 2010

September 16 - Balaenophilus manatorum

Balaenophilus manatorum is an ectoparasitic parasite of sea turtles and possibly manatees as well. Recently, specimens of this parasite were obtained from stranded loggerheads on the Spanish coast. Gross morphological and SEM studies could not distinguish these copepods from others that had been found on sea turtles off of Japan and so, for the moment, have been classified as that species. The parasites can be incredibly dense -the authors of this paper note that thousands were found on individual juvenile turtles. Other parasitologists have speculated that this species is the same copepod that has also been found on manatees in the Caribbean. Thus, either this parasite is very much a generalist or there are cryptic species yet to be determined.

September 15, 2010

September 15 - Entamoeba histolytica

Entamoeba histolytica is one of the most common parasites of humans and apes, with some estimates going as high as 50 million people infected worldwide. These single-celled amoebae are ingested as cysts that are shed in feces of other infected hosts. The protozoa excyst in the intestines and multiply there, usually resulting in symptoms ranging from mild diarrhea to full-on amebic dysentery. Eventually, they can bore through the intestinal wall and begin to infect other tissues such as the liver, spleen and brain. The amoebae will even gobble up red blood cells as seen in the photo (the dark circles in the outer two cells). Interestingly, it is now known that many suspected cases of E. histolytica that are based on microscopic examination are actually those of Entamoeba dispar, a benign species, which is actually up to 10 times more common that it's virulent cousin.

September 14, 2010

September 14 - Cystobranchus virginicus

Today's parasite may be an example of a parasite turned predator over the course of evolution. Cystobranchus virginicus is a fish leech (Family Piscicoloidae), similar to a leech we saw earlier this year. Like other fish leeches, C. virginicus supposedly uses its long proboscis to feed on fish blood. However, this leech also has been documented to feed on fish eggs, an infrequently documented behavior (egg-feeding had only been observed in 5 or 6 other leech species). During a study examining fish mating systems, C. virginicus appeared in the redds (gravel nests where fish eggs are deposited) of at least four different fish species. Although not actually observed feeding on the fish eggs, these leeches were distended in shape and had the same translucent yellow color as the fish eggs when collected. Interestingly, no one has ever observed C. virginicus feeding on fish blood. It’s possible that the entire diet of this leech now consists solely of eggs, a potential concern if egg feeding results in high mortality and decreased fitness of the host fish species.

Contributed by Jessica Light.
See this paper for more info.

September 13, 2010

September 13 - Paucivitellosus fragilis

Paucivitellosus fragilis belongs to a small family of digenean trematodes call Bivesiculidae. They are parasitic in the gut of marine fishes and unlike most other families of digeneans, they do not have a second intermediate host, but infect the fish host directly when the cercaria larval stage is ingested by the fish. Upon emerging from the snail first intermediate host (where the cercarial stages are produced via cloning), a structure call a caudal vesicle folds itself over the cercaria body like a sock, acting as a kind of protective wetsuit. It then begin swimming actively with vigorous vibration of its tail. After a few hours, it sticks itself either to some floating debris or the surface of rocks, waiting to be eaten by an unwary grazing fish.

Photo came from:
Abdul-Salam, J. and Sreelatha, B.N.S. (1996) Light and scanning electron microscopic observations of the rediae and cercariae of Paucivitellosus fragilis (Digenea, Bivesiculidae). Acta Parasitologica 41:108-114.

Contributed by Tommy Leung.

September 12, 2010

September 12 - Clonorchis sinensis

Today's parasite, the human liver fluke, Clonorchis sinensis infects 30 million people in parts of Southeast and East Asia such as Japan, Taiwan, and China. Like other trematodes, this fluke has a complex life cycle that begins when a freshwater snail consumes the egg and it hatches into a miracidium. They asexually divide in the snail and eventually produce redia, which leave the snail and seek out a fish. They bore into the muscles of the fish and form a resistant cyst. If a human consumes this fish, the parasites excyst in the small intestine and make their way to the liver. There, they will mature into adults, consume bile as their main food source, and crank out 1-2 eggs per minute. The worms can cause a variety of health problems in people.

September 11, 2010

September 11 - Crocodylocapillaria longiovata

A few months ago, you met Capillaria hepatica, a nematode worm that sometimes infects humans, but mostly uses rodents as its host. Today's parasite is Crocodylocapillaria longiovata, which is another Capillariid. This one, however, uses crocodiles, namely Johnston's Crocodile (Crocodylus johnstoni) and the biggest, nastiest crocodile of them all, the Saltwater Croc (Crocodylus porosus), as its hosts. These nematodes live in the stomach of the crocodiles and lay unusually long eggs (hence their specific name), which will eventually become embryonated, as seen in the drawing.

September 10, 2010

September 10 - Agema silvaepalustris

Pentastomids are a group of parasites that primarily infect the respiratory tracts of reptiles and amphibians, with a few species that infect birds and mammals (see Armillifer agkistrodontis). While they might look like worms, pentastomids are more closely related to arthropods, and they are ubiquitously found in the lungs of crocodiles. In fact, it's quite likely that every single species of living crocodilians is infected with pentastomids, indicating that these two groups have had a long co-evolutionary history which stretches back millions or possibly even hundreds of millions of years.

Today's parasite is Agema silvaepalustris and it is found in the lungs of the dwarf crocodile Osteolaemus tetraspis, which lives in the equatorial rain forest zone of West and Central Africa. The crocodiles become infected when they eat fish that possess the larval instars of A. silvaepalustris. The lungs of an individual crocodile can be infected with a few dozen to over a hundred of these parasites, and it is amazing to think that these weird little banana-shaped critters are more closely related to shrimps and crabs than any actual "worm"!

For further details, see:
Riley, J., Hill G. F., Huchzermeyer, F. W. (1997) A description of Agema, a new monotypic pentastomid genus from the lungs of the African dwarf and slender-snouted crocodiles. Systematic Parasitology 37: 207-217.

Contributed by Tommy Leung.

September 9, 2010

September 9 - Trichinella zimbabwensis

Parasitic nematodes in the genus Trichinella are commonly found in endothermic (warm-blooded) animals. The most common species, Trichinella spiralis, is found in many species of mammals. The infective larvae live in specialised capsules call "nurse cells" (which are muscle cells which have been heavily modified by the parasite), and they are transmitted into different mammalian host via carnivory or scavenging on carcasses. Trichinella zimbabwensis deviates somewhat from this pattern. While it is still transmitted to a new host via the ingestion of infected muscle tissue, unlike T. spiralis, it does not encapsulate and it is also found in reptilian hosts, specifically crocodiles. However, it does not occur exlusively in reptiles and can also infect mammals. Given that it is able to survive in both ectothermic and endothermic hosts, while other species of Trichinella can only survive in endothermic hosts in the wild, this raises intriguing questions about the evolutionary origin of the genus Trichinella.

For more details, see:
Pozio, E. et al. (2002) Trichinella zimbabwensis n.sp. (Nematoda), a new non-encapsulated species from crocodiles (Crocodylus niloticus) in Zimbabwe also infecting mammals. International Journal for Parasitology 32:1787-1799.

Contributed by Tommy Leung.

September 8, 2010

September 8 - Eimeria alligator

Eimeria is a genus of apicomplexan parasites, but are coccidia, so unlike their cousins such as Plasmodium and Babesia, which alternate between an insect vector and a vertebrate, these parasites are transmitted via the oral-fecal route. Eimeria alligator was described from American Alligators (Alligator mississippiensis) in 1990, after sampling gators that had been shot in Texas during the alligator hunting season. Seven other species of Eimeria have been reported from crocodilian hosts in both the New and Old Worlds, as have two species of Isospora, another genus of coccidia.

September 7, 2010

September 7 - Acanthostomum americanum

Acanthostomum americanum is a digenean trematode found in the intestine of Morelet's crocodile (Crocodylus moreletii) from Yucatan, Mexico. The crocodiles acquire this parasite when they eat fish that are infected with the parasite's encysted larval stages.The early juveniles of these worm are characterized by the lack of spines on the oral sucker, which is likely to be an adaptation which allows it to make a smooth seal with the intestinal wall before suction, which maintains the developing parasite in position between the intestinal villi. As the parasite grows, so do the spines around its oral sucker, which then take over the role of anchoring it firmly in the intestinal mucosa.

Image adapted from:
Moravec, F. 2001. Some helminth parasites from Morelet's crocodile, Crocodylus moreletii, from Yucatan, Mexico. Folia Parasitologica 48: 47-62.

Contributed by Tommy Leung.

September 6, 2010

September 6 -Haemogregarina crocodilinorum

There are five species of hemogregarine apicomplexan blood parasites (distant relatives of malaria parasites) that have been described from alligators and crocodiles. Haemogregarina crocodilinorum is the one that infects the American alligator, Alligator mississippiensis. This parasite is most likely transmitted by the leech, Placobdella multilineata, which is commonly found on alligators throughout the Southeast.

September 5, 2010

September 5 - Griphobilharzia amoena

Today's parasite is a schistosome blood fluke which has been described from the Australian freshwater crocodile (Crocodylus johnstoni). While most schistosomes are known from mammalian and avian hosts, Griphobilharzia amoena is found in a reptilian host. Like other schistosome (as opposed to most digenean flukes), G. amoena is dioecous (they have males [left] and females [right]). This fluke occupies an important position in terms of research into the evolution history of schistosomes; it has been hypothesised that the evolution of dioecy in these blood flukes was accompanied by the evolution of endothermy ("warm-bloodedness") in their hosts. With G. amoena being found infecting a crocodilian, it seems to suggest that the origin of dioecy dates back before the evolution of endothermy. However, in another twist, it has also been suggested that the ancestors of modern crocodiles were originally endotherms which had reevolved ectothermy ("cold-bloodness"). Appropriately, "Gripho" - which forms a part of this parasite's name, actually means "a riddle".

Description for Griphobilharzia amoena:
Platt, T. R., Blair, D., Purdie, J. and Melville, L. (1991) Journal of Parasitology 77:65-68.

The paper which suggest crocodiles reevolved ectothermy:
Seymour, R. S., Bennett-Stamper, C. L., Johnston, S. D., Carrier, D. R. and Grigg, G. C. (2004) Physiological and Biochemical Zoology 77:1051-1067.

Contributed by Tommy Leung.

September 4, 2010

September 4 -Corynosoma enhydri

This photo of today's parasite,Corynosoma enhydri, illustrates the origin of the term “thorny-headed worms” for the Acanthocephala. This species, like Profilicollis altmani, that you met last month, uses sea otters as its definitive host. It is fairly obvious that once this proboscis is embedded in the wall of the small intestine of a sea otter, it could not easily be dislodged. In rare cases, the proboscis can perforate the wall of the intestine, leading to peritonitis. The number of rows of hooks on the proboscis and the number of hooks per row are important characters in identifying species.

Contributed by Mike Kinsella.

September 3, 2010

September 3 - Liriopsis pygmaea

Parasites don't always have things go their own ways. Even in the parasite world, sometimes the hustler gets hustled. There are parasites which specifically infects other parasites, called "hyperparasites" and Liriopsis pygmaea is one such example. The false king crab Paralomis granulosa is host to a rhizocephalan parasite called Briariosaccus callosus which belongs in the same group of parasitic barnacles as Sacculina carcini (which we met back in January 7).

Liriopsis pygmaea attaches itself to the externa of B. callosus and parasitises it (see pale blobs in photo, arrow indicating externa of B. callosus). L. pygmaea belongs to the group of isopods call the cryptoniscid. While most people are familiar with isopods in the form of slaters and pillbugs you see in the garden, adult L. pygmaea bears a closer resemblance to the cherry tomatoes which might be growing in the said garden than their isopod cousins. Just as B. callosus castrate its crab host, L. pygmaea does the same to the rhizocephalan - drawing resources away from the parasitic barnacle and using it for its own reproduction. So in this case, the castrator, becomes the castrated.

The photo and the info for write up came from this paper:

Lovrich, G. A., Roccatagliata, D., Peresan, L. (2004) Hyperparasitism of the cryptoniscid isopod Liriopsis pygmaea on the lithodid Paralomis granulosa from the Beagle Channel, Argentina. Diseases of Aquatic Organisms 58:71-77.

Contributed by Tommy Leung.

September 2, 2010

September 2 - Bdellovibrio bacteriovorus

When I was teaching microbiology, Bdellovibrio was always one of my favorite things to lecture about. These bacteria are essentially intracellular parasites of other bacteria. Bdellovibrio has a rather unusual mode of entering its hosts - it uses its flagellum to crash into them at amazing speeds - 160 um/second (ok, that doesn't sound very fast, but when you're only about 1 micron long, that's hauling!) Once inside its host cell, the Bdellovibrio consumes the nutrients inside it, growing longer and longer the whole time. Eventually, when the host cell has run out of nutrients, the long filament will separate into about 3 to 6 individual cells, lyse the membrane of their former host and go off and infect new victims.

September 1, 2010

September 1 - Dactylanthus taylorii

Dactylanthus taylorii is a holoparasitic plant, meaning that it does not possess any chlorophyll of its own and derives all of its nutrients from its host plant, which is commonly the Seven-finger (Schefflera digitata). When infected, the host tree will produce a malformation, or burl, that resembles a wooden rose, hence its common name, the Wood Rose. The flowers are pollinated by the Lesser Short-tailed Bat (Mystacina tuberculata), which are drawn to its odor and abundant nectar. This species, native to New Zealand, is sadly critically endangered there and is the subject of aggressive conservation plans.