Sunday, December 12, 2010

Caterpillar communication



"Explain yourself!," said the caterpillar in Lewis Carroll's Alice in Wonderland (1st image). Well, it turns out that several species of caterpillars - including the silkmoth (2nd image) - can do just that:
  • The Walnut Sphinx caterpillar (Amorpha juglandis) whistles, letting out squeaks that startle and scare off attacking birds. By pulling its head back to compress its body cavity, it forces air out holes in its sides known as spiracles. Researchers at Carleton University determined that the whistles came from the 8th pair, lasting up to 4 seconds each, and spanned frequencies ranging from those audible to birds and humans up to ultrasound. (Watch and listen here.)
  • The Masked Birch caterpillar (Drepana arcuata) taps and scrapes to communicate its ownership of a leaf. If tapping its mandible doesn't deter the intruder, it makes complex vibratory signals by dragging hair-like structures on its back end to make a scraping sound. (Watch and listen here.)
  • The Common Silkmoth caterpillar (Antheraea polyphemus) deters predators with clicks of its mandibles, warning that it is about to release a foul brown fluid. Their mouths are covered with serrated, tooth-like ridges and, with their soft bodies, "they don't have much other than their mandibles to scrape together to make sounds," explains Jayne Yack of Carleton University. The clicks, which sound like the ticking of a watch, are loud over short distances but don't carry far. (Watch and listen here.)
  • The Mountain Alcon Blue caterpillar (Phengaris rebeli, formerly Maculinea rebeli) hisses and ticks in imitation of the ants with which it has a parasitic relationship. It tricks the ants into believing it is the larva of a queen ant, so they carry it to their nest and carefully protect and feed it. "They appeared to be treating the caterpillars as if they were the holiest of holiest, the pinnacle of power, the queen ant," says entomologist Jeremy Thomas of the University of Oxford. (Listen here.)
The Tobacco Hornworm caterpillar (Manduca sexta) and the Luna Moth caterpillar (Actias luna) also made warning clicks. Videos presumably forthcoming from Carleton University...

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