Friday Parasite #37: More on Taenia

Last week featured a gorgeous picture of Taenia pisiformis. It’s a tapeworm which lives inside carnivores like dogs, foxes, and coyotes, hooked into the intestinal wall at its head and dropping egg-filled body segments called proglottids off its rear end.

The tapeworm eggs leave a dog in its droppings but interestingly, despite dogs' appalling coprophagic habits, they don’t reinfect dogs directly. Instead, the tapeworm eggs attach themselves to blades of grass and wait to get eaten by a rabbit. In the rabbit, they hatch into a larval form, burrow through the rabbit’s gut, and attach themselves to the surface of its internal organs. There, they encyst themselves and wait for the rabbit to become prey.

But rabbits don’t eat grass that’s been besmitched with dog poo. So how do the tapeworm eggs manage to get from inside the dog droppings to some clean grass a rabbit might find attractive? Turns out they come in a mobile container. After it’s dumped outside, the proglottid begins to crawl away. The School of Veterinary Medicine at the University of Pensylvania has a video of a moving proglottid that shows you how it works. It's worth checking out.

Comments

[Emily]

EWWWWWW!
(But cool!)

[Drhoz!]

brilliant!