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Moths of the Hawaiian genus Hyposmocoma are an oddball crowd: One of
\nthe species’ caterpillars attacks and eats tree snails. Now researchers
\nhave described at least a dozen different species that live underwater
\nfor several weeks at a time.<\/p>\n
"I couldn’t believe it," said study
\ncoauthor Daniel Rubinoff, an evolutionary biologist at the University
\nof Hawaii at Honolulu, of the first time he spotted a submerged
\ncaterpillar. "I assumed initially they were terrestrial caterpillars .
\n. . how were they holding their breath?"<\/p>\n
Each of the 12 species
\nlives in and along streams running down the mountains on several
\ndifferent islands of Hawaii, said Rubinoff, who has studied
\nHyposmocoma, a group of more than 350 moth species, for more than seven
\nyears. <\/p>\n
They usually eat algae or lichen, and build silk cases
\n— which one species even adorns with bird feathers — for shelter and
\ncamouflage. They spin silk drag lines to withstand the high pressure of
\nfast floodwaters.<\/p>\n
Unlike other amphibious creatures that can
\nsurvive underwater on stored oxygen but must come back up for air,
\nthese caterpillars can spend several weeks without ever breaking the
\nsurface, according to the paper, which was published online on Monday
\nin Proceedings of the National Academy of Sciences.\n<\/p>\n
It isn’t yet
\nclear how the insects do it. Rubinoff and co-worker Patrick Schmitz of
\nthe University of Hawaii did not find any water-blocking stopper over
\nthe caterpillars’ tracheae or evidence of gills. The animals drowned
\nquickly when kept in standing water, so they seem to need the higher
\nlevels of oxygen present in running water, and probably absorb it
\ndirectly through pores in their body, the scientists said. <\/p>\n
The
\ntrait appears to have evolved more than once, Rubinoff said. After
\nanalyzing the DNA of the 12 amphibious species, the scientists found
\nthat three separate lineages of moth had developed the ability to
\nbreathe underwater at different points in the past. <\/p>\n
Why they
\nevolved this trick isn’t clear, but animals and plants are known to
\noften evolve in surprising directions after arriving at new, sparsely
\npopulated habitats such as islands, said Felix A.H. Sperling, an
\nentomologist with the University of Alberta in Edmonton. <\/p>\n
In a
\nnew environment, released of the pressure of having to fight for food
\nsources or evade predators, they are freer to expand into new niches. <\/p>\n
"When
\nthe pressures on an environment are released, what crazy things are
\nanimals capable of doing?" said John W. Brown, a research entomologist
\nwith the U.S. Department of Agriculture. <\/p>\n
"You just wonder . . . do all animals have that potential?"<\/p>\n
— Amina Khan<\/p>\n
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