Jul 30, 2009

Tonic Immobility

The old joke goes something like this: Two hikers encounter a hostile bear in the woods. One immediately kneels to tie his shoe laces. His companion says, "What are you doing? Do you honestly think you can outrun a bear?"
The first hiker says, "Nope. All I have to do is outrun you."

The same situation applies here, only opposite. When Adanson's house jumping spider seeks out its preferred prey, the red flour beetle (such domestic names...), it prefers living beetles over those which are dead...or which feign death. So in this instance, the first beetle doesn't need to be faster than the second beetle; he needs to look deader.

Photo source: LiveScience.com

Takahisa Miyatake of Okayama University in Japan has been studying the red flour beetle for years. He has developed two strains of them: one that will feign death for 20 minutes, and one that won't feign death at all. So, what happens when Adanson's house jumper goes on the prowl among these two groups? Well, that spider is only 38% likely to eat a 'dead' beetle if there isn't a living, non-feigning one around. But if there is a living, wriggling one nearby, that same spider will go for it nearly every single time.

Feigning death (technically called 'tonic immobility'--great name for a rock band) seems to work like a charm among these beetles, especially if the beetle next to you is a chump that doesn't know when to lie low.

Thanks for the article, Ida.

1 comment:

Anonymous said...

Dude, this is TOTALLY what I did to waste... I mean, pass the time in the college lab. Toss the exact same red flour beetles and black weevils to the daddy longlegs webs and watching the fun.

Juice-suckers grew pretty fat by the time I left the place...