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Lauren Admire | 29 Mar 2010 21:00
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First Amphibious Insect Found in Hawaii

The freshwater streams of Hawaii host a strange sort of insect: a caterpillar of the genus Hyposmocoma, that is happy both under water and on land. So far, this is the only insect we know of that is truly amphibious.

"When you put these guys in water, they run around and eat," explains study co-author Daniel Rubinoff. "You take them out, and they're perfectly fine too. No other insect that we're aware of can do that. Actually, no other animal that I'm aware of can do that."

There are a few examples of animals with amphibian-like qualities: Some beetles can survive underwater by entering into a dormant state, and lungfish can breathe on land by forming mucus lined cocoons, but neither functions normally when out of their preferred environment.

It's unknown how the Hyposmocoma caterpillars are able to function so well underwater. They spend their lives in a cocoon of hardened silk, and it was believed that air pockets were forming within it, allowing them to survive underwater for an undetermined amount of time. However, when the cocoons were dissected underwater, no bubbles rose to the surface, indicating that the supposed air pockets did not exist. The caterpillars must use some other way to breathe underwater.

"It may be a specialized organ that we haven't found, or it may be that their skin is thinner than terrestrial [caterpillars], which permits them to breathe directly through their skin," Rubinoff said.

If thin skin is the reason behind their amphibious nature, it might explain why they are only found in fast-flowing streams, which carry highly oxygenated water.

Source: National Geographic

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