The Word of the Law is (Not Yet) Thelema
BY ALPER ÖZKAN (MSN/PhDII)
Welcome, once again, to a parasite column! I have just recently managed to survive a horrid nightmare of a week only to plunge straight into yet another maelstrom of several deadlines strung together into a perfect chain of sleeplessness, so I cannot exactly perform the research required to write a column on subjects I am not particularly learned about (you might have noticed that this is my excuse about every other fortnight, but do recall that graduate life is not exactly a breeze). Thus, though this week's column was originally dedicated to secret cults, number magic and Aleister Crowley's amazing pyramid hat, my quest to find the gematric equivalent to my name and ascribe some profound magical significance to it will have to hold off until next time (there's this online calculator that equates my name to Lilith, mother of all demons, and/or a word originally meaning "owl" after a couple millennia of misunderstandings, but I don't trust that calculator very much), and since "when in doubt, write about parasites" is my motto when it comes to columns put together in haste, you'd better brace yourselves for another week of various critters who have made it their mission in life to sneak undetected into other living things doing their darndest to get them out.
This modus vivendi naturally necessitates a degree of craftiness. It is obviously beneficial for a parasite to manipulate its host, if only to coax it into picking the parasite up -- all parasites are required to physically get on or into the animal they are parasitizing, and endoparasites in particular aren't very (or at all) mobile. To further complicate matters, many use several hosts before settling down in their fleshbound home, utilizing one or more intermediate hosts and (usually) moving up the food chain until they are ultimately consumed by a final host. For most parasites, merely getting into a delicious-looking morsel is enough to fool a hapless bird or beast into devouring a mouthful of them, but others don't want to leave their fate to the caprices of predator-prey interactions -- and it is here that many curious cases of host manipulation can be seen.
A familiar example is the lancet liver fluke. First hatching in snails, the young flukelets are encased in the snail's slimy secretions and left to their own devices as the troubled gastropod tries to ease itself of its parasitic burden, though at the peril of another organism: ants who eat the cysts left in the snail's wake are the fluke's new victims, with all but one juvenile fluke forming new cysts in the ant's body, while the remaining loner moves to the ant's nervous system to execute the next step of the fluke's plan, puppeteering the ant to fulfill its own goals. The infected ant is uncoordinated and acts drunk even even during the day, but the effects of the mind fluke are most clearly seen during the night, when the infectee leaves the safety of its colony, climbs a blade of grass and clamps down until dawn (mornings are too hot for the fluke's comfort). It continues its nightly sojourns until it is eaten by a grazing sheep or cow, where the flukes are free to leave their cysts, move to the liver and show the poor ruminant why they're called liver flukes.
Other parasites, however, have much more interesting takes on host manipulation. While it does force ants to get themselves eaten, the liver fluke at least has the decency not to turn its victims into freaks of nature -- unlike its equally famous fellow trematode Leucochloridium, which takes root in the eyestalks of snails and converts those structures into massive, pulsating lumps that look like billboard advertisements for an all-you-can-eat buffet to any bird passing by. Yet another internet-famous trematode, Ribeiroia, makes frogs grow extra legs, and, while this is rather disconcerting to the human eye, birds don't seem to particularly dislike eating these mutated monster frogs, which they catch with ease because all the extra baggage (leggage?) slows down the animal. Slightly more obscure are certain blister beetle grubs that crawl together to create a ghoulish semblance of a female bee, which is convincing enough to male bees that the latter try to mate with the larval mass -- and in doing so pick up the parasitic larvae, which later crawl onto a real female bee when the male finds one and hitchhike on the female to reach their actual target: the female's nest and the defenseless young within.
What if the parasite doesn't want to be eaten? A wasp and a midge both seem to have found the solution: Macrodasyceras hirsutum and Asphondylia ilicicola explicitly don't want to get their hosts eaten, since they complete their development in the fruit they infect -- so they simply prevent it from ever becoming attractive to birds. While the mature berries of holly trees are bright red, infected fruits become an equally bright green, advertising their supposed unripeness to any animal that might otherwise take an interest in the fruit and devour both it and the insect contained within.
That's it for this week! The next installment, as mentioned, will feature some real-life cult drama, so do look forward to it.