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The Honolulu Advertiser
Posted on: Tuesday, March 23, 2010

Amphibious caterpillars found

By Eloise Aguiar
Advertiser Staff Writer

Hawaii news photo - The Honolulu Advertiser

A moth larva in a “bugle” case reattaches itself to an underwater rock. The caterpillars are of the genus Hyposmocoma, unique to the Hawaiian Islands. No other insects are equally at home in or out of the water.

Photos by Patrick Schmitz and Daniel Rubinoff

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Hawaii news photo - The Honolulu Advertiser

P. Schmitz collects caterpillar cases in a stream.

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Hawaii news photo - The Honolulu Advertiser

“Burrito” cases resting communally. The cases are named for their shapes.

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University of Hawai'i researchers have discovered Hawaiian moths that can live a part of their life cycle underwater or on land.

Daniel Rubinoff and Patrick Schmitz yesterday reported their findings online in the Proceedings of the National Academy of Sciences, initiating media calls from around the world, including Russia, France, Britain and Japan, said Rubinoff, assistant professor in the UH Department of Plant and Environmental Protection Sciences.

They discovered that the caterpillars of 12 species of the Hyposmocoma moth have the ability to live submerged or on dry land.

"They can stay underwater for an indeterminate period of time, or out of the water," said Rubinoff, an entomologist. "There's no other animal that I'm aware of that can do that."

Rubinoff is still studying how the caterpillar survives under water. He said other caterpillars have gills, but he thinks this creature is breathing through its skin.

"They need to be in fast-moving streams which have a lot of oxygen in them," he said.

Hyposmocoma moths share a common trait, Rubinoff said. The caterpillars spin their cases out of silk, and whatever materials that are nearby such as pebbles, shells or algae. They are grouped according to their shape. Burrito-, bugle- and cone-shaped cases are found near streams and volcanic rocks.

But he found several land caterpillars, anchored by silk threads to rocks, in streams, and they seemed to survive well there, he said. Tests proved that they were equally comfortable out of the water.

Rubinoff has been studying the Hyposmocoma since 2002. In this recent paper, he has over 200 moth samples from 89 recognized species. The new discovery is part of the research into the evolutionary history of the genus, Rubinoff said.

Since he began his work, he has also announced the discovery of eight new species of that genus on three islands in the Papahānaumokuākea Marine National Monument. In 2005, he reported finding caterpillars of other species that eats snails.

"There's a lot of diversity in this group," he said.

The Hyposmocoma is found only in Hawai'i. The insect arrived in the Islands about 20 million years ago and evolved into 400 species, doing things no moth any where in the world does, he said, adding that every species is only found on a single island. It makes Hawai'i a unique research center, Rubinoff said.

"It will help us understand more broadly how evolution works, how all these species fit together," he said. "So Hawai'i has the ability to inform the world as a whole in this way, and I think that's pretty special."