By REBECCA KESSLER - AAAS
Added: Sun, 10 Jul 2011 14:30:38 UTC

Lucky shots. The first photos of a tool-using fish in the wild show a blackspot tuskfish banging a clam against a rock to crack it open. Credit: Scott Gardner

While exploring Australia's Great Barrier Reef, professional diver Scott Gardner heard an odd cracking sound and swam over to investigate. What he found was a footlong blackspot tuskfish (Choerodon schoenleinii) holding a clam in its mouth and whacking it against a rock. Soon the shell gave way, and the fish gobbled up the bivalve, spat out the shell fragments, and swam off. Fortunately, Gardner had a camera handy and snapped what seem to be the first photographs of a wild fish using a tool.

Tool use, once thought to be the distinctive hallmark of human intelligence, has been identified in a wide variety of animals in recent decades. Although other creatures don't have anything quite like a circular saw or a juice machine, capuchin monkeys select "hammer" rocks of an appropriate material and weight to crack open seeds, fruits, or nuts on larger "anvil" rocks, and New Caledonian crows probe branches with grass, twigs, and leaf strips to extract insects. In addition to primates and birds, many animals, including dolphins, elephants, naked mole rats, and even octopuses, have shown forms of the behavior.

Tool-using fish have been few and far between, however, particularly in the wild. Archerfish target jets of water at terrestrial prey, but whether this constitutes tool use has been contentious. There have also been a handful of reports of fish cracking open hard-shelled prey, such as bivalves and sea urchins, by banging them on rocks or coral, but there's no photo or video evidence to back it up, according to Culum Brown, a behavioral ecologist at Macquarie University in Sydney, Australia, and a co-author of the present paper, to be published in a forthcoming issue of Coral Reefs.

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TAGGED: BEHAVIOR, BIOLOGY