|photo credit: Don Ward|
Maria Sala-Bozano/University of Salford
One of the parasitic crustacean is the infamous tongue-biter, which was the subject of the next talk by Melissa Martin. Her study focused specifically on Cymothoa (the tongue-biter genus) in Australian waters. While most people are intrigued/horrified by their creepy mouth-dwelling antics, it turns out Cymothoa also have an interesting sex life.
The individual that act as the "prosthetic tongue" is always a female and she can produce hundreds of eggs in a brood sac on her belly. The sex of a newly arrived Cymothoa is actually dependent on whether the fish is already carrying another tongue-biter. If there is already a female sitting in the host fish's mouth, the new arrival turns into a male and mates with the female. If another juvenile Cymothoa comes along, the Johnny-come-lately will turn into a male, but he doesn't get in the way of the first male. Instead, he waits in line and if the original female dies, the first male will turn into a female and take her place on the fish's atrophied tongue
Later in the session on parasites of aquatic wildlife Katie O'Dwyer talked about her research was on a species of philophthalmid fluke. The species she is studying is in the same family as a eye fluke that we have previously featured on this blog and is also found in the Otago Harbour. But instead of infecting the mud snail (Zeacumantus subcarinatus) which are abundant on the mudflats of Otago Harbour, this species infects two species of perwinkles - the Banded Periwinkle (Austrolittorina antipodum) and the Brown Periwinkle (Austrolittorina cincta) found on the rocky shores of New Zealand.
|Left: Philophthalmid rediae in snail|
Right: Philophthalmid larva encysted on a Petri dish
During the day, I checked out some posters on thorny-head worms of marlin, trematodes in wrasses of the Great Barrier Reef, worms in dingoes, blood parasites in gobies and coccidians in small mammals. A poster that really caught my attention was one by Amanda Worth, questioning whether the interpretation of altered behaviour in rodents infected with Toxoplasma gondii has simply been a story which has been overblown due to its appeal. It questions whether the role that cats play in the life cycle of T. gondii has been over emphasized seeing as the parasite is capable of being transmitted between hosts just fine without a cat being involved. There's no denying that T. gondii can indeed alter rodent behaviour, but whether it is actually adaptive for the parasite to do so or if it is simply a side effect of the infection pathology should be reevaluated. While T. gondii is often cited as a classic example of parasite host behavioural manipulation, is it because the evidence supporting such an interpretation are really compelling or if it is simply a story that has all the elements that makes it an appealing to us (C'mon, cats AND mind-controlling/zombifying parasites)?
|Photo credit: Stefan Kraft|
For a change of pace, Linda Ly presented research on parabasalid flagellates from some Australian termites. Those flagellates are not quite parasites and might actually be mutualists, but they are still very interesting. In a single termite species she was able to identify at least ten brand-new morphotypes of flagellates and considering there are 260 species of native Australian termites in total, those ten are just the tip of the diversity iceberg for termite gut flagellates. This was followed by a talk from Edward Green about some of the morphological features of the springbok louse Linognathus euchorse and the session ended with Mary Shuttleworth presenting her research on the hidden genetic diversity and structure of Cloacina - a genus of parasitic nematode found in swamp wallabies.
While the majority of the talks were on veterinary parasitology, which as I mentioned in my previous post was not really my scene, there were plenty at the conference which held my interest the entire time. This post is only a very small and selective sampling of a fairly well-attended international conference. We will be back with the usual parasite posts next month - I already have a few papers lined up to write about so watch this space!