Light triggers eyeless hydra to sting prey - George Foulsham - Futurity.org

By GEORGE FOULSHAM - FUTURITY.ORG
Added: Thu, 08 Mar 2012 16:01:50 UTC

Thanks to Mike OHare for the link.

"Hydra stinging cells were already known to be touch sensitive and taste sensitive, but no one had ever thought before to look for light sensitivity—probably because they don’t have eyes," says Todd Oakley. "We're the first to have found that. And we found not only that light-sensitivity genes are expressed near hydra stinging cells, but that under different light conditions, these cells have different propensities to be fired." (Credit: David Plachetzki)

Hydra, a freshwater polyp—along with jellyfish, sea anemones, and corals in the Cnidaria family—use stinging cells, or cnidocytes, to catch prey. Hydra tentacles contain barbed, poison-containing cnidocytes that they use to stun animals, such as water fleas and plankton, before eating them alive. They’re also used for self-defense and locomotion.

New research reported in the journal BMC Biology, reveals that light, or the lack thereof, has a direct effect on hydras’ propensity to fire their stinging cells—a discovery that “tells us something completely new about the biology of these animals, and we think this could extend to other cnidarians,” says Todd Oakley, professor of ecology, evolution, and marine biology at the University of California, Santa Barbara.

“Hydra stinging cells were already known to be touch sensitive and taste sensitive, but no one had ever thought before to look for light sensitivity—probably because they don’t have eyes,” he says. “We’re the first to have found that. And we found not only that light-sensitivity genes are expressed near hydra stinging cells, but that under different light conditions, these cells have different propensities to be fired.”

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TAGGED: BIOLOGY, EVOLUTION, SCIENCE

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