Science Diary: Caterpillars - Frass Thrower: The Pulse of the Planet daily radio program offers free legal online mp3 downloads, exploring the world of sound in nature, culture and science, with audio adventures, world music, extraordinary sound portraits, science diaries, and nature ring-tones; an amazing sonic experience.



Airdate: Oct 28, 2008
Scientist: Grant Gentry

Science Diary: Caterpillars - Frass Thrower

Science Diary: Caterpillars - Frass Thrower
For some caterpillars, self-defense can be a real crapshoot!

Transcript:
Science Diary: Caterpillars - Frass Thrower

Music; Ambience: morning rainforest, Tirimbina, Costa Rica, birds, insects

Gentry: So if you're a caterpillar, and you don't want to get parasitized, you want to keep as far away from your poo as possible.

Welcome to Pulse of the Planet's Science Diaries, a glimpse of the world of science from the inside. Grant Gentry is a tropical ecologist at Samford University who studies caterpillars in the rainforests of Central America. Caterpillars have adopted many strategies to keep from being killed by predators including parasitoids tiny critters that want to deposit their eggs and larvae inside the caterpillar. And some of the caterpillar's defense strategies are inventive, to say the least.

Gentry: There's these caterpillars that are the caterpillars of skippers, which are kind of a cross between a butterfly and a moth. And a lot of them can shoot their frass, it's called frass, it's their poo. They can shoot their poo. They can do it either by flicking it with a specialized little frass flicker on their hindmost segment, or they can shoot it by pressurizing their colon. Some of these skipper caterpillars can shoot it for like, a meter. It would be like, you know, you or me being able to shoot our poo the length of a football field. Now, the reason they do that we think, is because poop stinks. And parasitoids have incredibly sensitive chemosensory apparatus on their antennae. They can sense odors or chemicals in this poo from a long way away. So if you're a caterpillar, and you don't want to get parasitized, you want to keep as far away from your poo as possible. There's a lot of them that actually make a shield with poo. I think that's to confuse parasitoids, because when they get there, they're just surrounded in signals.

They're surrounding themselves with smelly decoys to confuse and misdirect the sniffing parasitoids. We'll hear more about the ecology of the rainforest in future programs. Our latest project is a competition for third to sixth graders. Check out kidsciencechallenge.com. Pulse of the Planet's Science Diaries are made possible by the National Science Foundation.