August 31 - Placobdelloides jaegerskioeldi

Yesterday, you met Oculotrema hippopotami, a parasite of hippos that lives under their eyelids. Now, today, meet a parasite from the other end. The leech, Placobdelloides jaegerskioeldi, lives in the last 10 centimeters of the rectum of hippopotamuses and feeds on blood through that delicate tissue. A few years ago, I did some pretty exciting fieldwork in South Africa collecting these critters with Mark Siddall. But, don't worry - it was not necessary for anyone to reach up into the backside of any hippos (nor distract them on the other end). We were able to obtain some specimens when a nuisance hippo had to be culled by the Park Service there and the rangers very kindly removed some tissue with leeches attached for us (click on photo for a better view of the adult plus several of its offspring). However, we still spent a very harrowing morning poking around a river, looking for more samples, with hippos just 30 feet away or so. These leeches were collected as part of a larger project that we were conducting on the endosymbiotic bacteria that they have.

August 30 - Oculotrema hippopotami

The hippopotamus is notorious for being one of (if not the most) dangerous large animals of Africa, as they are extremely aggressive and unpredictable, and are responsible for killing more people than some of the iconic predators of Africa such as lions and crocodile. However, even this fierce giant is ailed by a tiny irritant - Oculotrema hippopotami - a species from a group of ectoparasitic flatworms known as the monogeneans.

Most monogeneans live on the skin or gills of fish, however there is an unusual family of monogeneans called the polystomatids that live mostly in the bladder of frogs and turtles. O. hippopotami can be considered even more of an oddball out of a family of oddballs. Not only has it colonised a mammal, it also lives in a peculiar part of its host. As its name implies, it lives in proximity of the hippo's eye, more specifically, under the eyelids. So for all its brazen brawn and strength, the mighty hippo is not immune from being parasitised!

Photo is from this site.

Contributed by Tommy Leung.

August 29 - Linguatula taenioides

Linguatula taenioides is a species of pentastomid worm that alternates between an herbivorous mammal (e.g. sheep) and a carnivorous mammal (e.g. wolf). The adults, which can be quite large - we're talking females that can be 4 inches or so! - live in the nasal passages. The eggs are sneezed out where they get eaten by grazing or browsing animals. Once into the gut of this intermediate host, the larvae, armed with two short claw-like arms, bore through the tissue of this host until they find a place to reside such as the liver or the lungs. There they encyst and wait for the host to be eaten, when they will repeat this process until they get to the lungs or nasal passages of the carnivore and mature into sexually reproducing adults.

August 28 - Cyttaria espinosae

Here's another parasite that people eat on purpose. Cyttaria espinosae is a fungus that is a parasite of beech trees (Nothophagus) and is native to Chile, where locals call it Digüeñe, Lihueñe or Quideñe. The fungus produces fruiting bodies that look remarkably like golf balls - and for a similar reason. The little divots in the fruiting body seem to promote air flow around them - which helps the fungal spores disperse in the wind. Locals like to serve them in salads and it supposedly has a gelatinous texture.

August 27 - Crataerina pallida

Crataerina pallida or the swift lousefly, is a hippoboscid fly that feeds off the blood of swifts that are found in Europe and Asia. The life cycle of the parasite is synchronized with the life cycle of the birds. In the late summer, the flies produce larvae (not just eggs), that will pupate and basically hang out like that over the winter in the birds' nests. The next spring, when the birds lay a new batch of eggs and the hatchlings are present, the flies will finish their development, feed off the baby birds and their parents, and begin the cycle all over again.

August 26 - Plasmodium malariae

Plasmodium malariae is another of the five species of Plasmodium that cause the disease malaria in humans, but this is the one you need to worry about least. It's not because it's only found in a tiny area - to the contrary, it has an almost worldwide distribution. But, the symptoms that it produces are fairly mild and it's rarely fatal. The fevers induced from infection with P. malariae occur every three days, thus it was known as "quarten" malaria in the ancient world (the Romans did not use zero). A species originally isolated from New World monkeys known as Plasmodium brasilianum was recently found to be genetically indistinguishable from P. malariae and probably represents a shared parasite, though the order of the move is still somewhat uncertain, i.e. whether human infections in the New World have recently spilled over into monkeys or whether this is a recent zoonosis acquired by humans.

August 25 - Ixodes holocyclus

This tick, the most commonly found tick along the east coast of Australia, is sometimes called the "Paralysis Tick" due to the unusual symptoms that it can produce in some people. Ixodes holocyclus lives in the wet forests, primarily, and would prefer to feed on Australia's charismatic marsupials (koala, kangaroos, etc), but will readily take its blood meal from humans if it encounters one instead. Toxins in the tick's saliva seem to disrupt neurotransmitters and can produce paralysis in humans, dogs, or other hosts and this can even be fatal if not treated because the paralysis can include muscles for pretty important things like breathing, swallowing and circulation. That said, paralysis from these tick bites is fairly rare, as it is necessary for the tick to remain attached for many days before the toxins will have these kinds of effects, so careful inspection of yourself or pets if in the area can literally be a life-saver. The good news is that there is an antiserum that can be administered if paralysis does set on. The image is a nice example, too, of how drastically different in size a tick will be before and after their blood meals.

August 24 - Thyca crystallina

Thyca crystallina is a tiny little limpet mollusc that lives on and sucks the "blood" - the hemolymph - out of blue sea stars (Linckia laevigata). The females of this species can become permanently attached to the exoskeleton of the echinoderms and just live their happily, feeding - oh and mating - with a tiny little male, one-tenth their size, that just lives in their shells and fertilizes her eggs. One might say that they are sort of a "tick of the sea" (oh, this really ought to confuse Jessica Simpson).

The image comes from this site.

August 23 - Lobatostoma manteri

Lobatostoma manteri is a species belong to a group of parasitic worm call the Aspidogastrea. The aspidogastreans are a very ancient group of parasitic flukes and are the sister group to the far more numerous and diverse digenean trematodes. In contrast to the digeneans which have a 3-host life-cycle (or variations on such), aspidogastreans only have 2 hosts in their life-cycle with the larval stage living in a mollusc and the adult living inside the gut of fishes. Unlike their digenean cousins, aspidogastreans do not asexually multiply within the mollusc host.

Lobatostoma manteri itself can be found on many tropical islands on the Great Barrier Reef of Australia. The definitive host for Lobatostoma is the Snubnosed Dart, Trachinotus blochi, from which the parasite's eggs are shed into the surrounding water. Marine snails become infected when they ingest the eggs and the larvae hatch from the eggs then develop into juvenile stages within the snail, which are in turn eaten by the Snubnosed Dart. L. manteri is very host-specific to this fish host because only that particular species of Dart has the well-developed pharyngeal plates (special teeth found in the throat of some species of fish) necessary to crack the hard shells of snails.

While it is a popular (and misguided) belief that the evolution of parasitism results in a lost of morphological complexity, this is a misconception, as the lost of certain sensory organs (such as eyes) which not necessary for navigating within the body of the host are replaced by the evolution of other sensory systems which are more appropriate for such an environment. Lobatostoma manteri has a complex and extensive nervous system, and the surface of the larval stage is dotted with over 8000 sensory receptors, with the adult (which grows to 4 mm in length) estimated to be covered in 20000-40000 receptors!

Contributed by Tommy Leung.

August 22 - Cuculus fugax

We have met other cuckoos before, birds that are known as brood parasites that usurp other birds' nests and trick them into raising their chicks instead of their own. Cuculus fugax, commonly known as Hodgson's Hawk-cuckoo, is a native of Southeast Asia that proves in a way that birds are pretty hard-wired and easy to fool. The parasitic bird lays one egg in the nest of another bird and when it hatches, it kicks any resident chicks out of the nest. And then it begs its new parents to feed it. But, the little chick is tricky - because it now only has one mouth gaping open for the parents to see, it also flashes the undersides of its wings, which have patches that look like two other chick mouths. The parents then go out and forage for three hungry chicks, bringing back enough food to feed the hungry cuckoo.