Biologists have discovered a new species of caterpillar in the Hawaiian rain forest that ensnares snails in silken webs, then feasts on them like a famished cannibal until nothing but the shell is left.
It's the first time such behavior has been documented in caterpillars - or any other member of its biological order, Lepidoptera, which includes moths and butterflies.
"It was like finding a wolf that dives for clams," said University of Hawaii biologist and entomologist Daniel Rubinoff, who reported the discovery with William P. Haines, a biologist at the university, in Friday's edition of the journal Science.
Although all caterpillars have silk glands, this species is the first to be seen using that organ like a spider. And although nearly all Lepidopterans are vegetarians, "This caterpillar wouldn't sample foliage even if it were starving," Rubinoff said.
Rubinoff said the new species, Hyposmocoma molluscivora, would not have been able to develop such a novel feeding strategy without the isolation of the Hawaiian archipelago.
That isolation, as Charles Darwin noted in his 19th-century study of the Galapagos Archipelago, favors the evolution of unique species, giving them millions of years of relaxed ecological competition in which to develop new ways of milking the most out of their environment.
With the destruction of much of the caterpillars' lowland habitats by modern human encroachment, that isolation might have ended, Rubinoff said.
A portion of the caterpillar's habitat, however, is still protected, giving researchers "the chance to decipher more of their mysteries," Rubinoff said. "We may find yet other novel, uniquely Hawaiian species."