☛ ScienceNOW: “Diver Snaps First Photo of Fish Using Tools” by Rebecca Kessler, July 8, 2011

The title is misguiding: it should at least ends with a question mark. Fortunately, the article provides adequate precisions about the controversy surrounding this finding in particular and the use of tools by animal in genreal:

Primatologist Elisabetta Visalberghi of the Institute of Cognitive Sciences and Technologies in Rome is less convinced. Visalberghi, who documented the hammer-wielding monkeys, adheres to a stricter definition of tool use that requires the animal to hold or carry the tool itself, in this case the rock. “The form of tool use described [in tuskfish] is cognitively little demanding and present in a variety of species. Often it has been labeled as proto-tool use because the object used to open the shell is still, fixated to the sea bottom, and not portable as stone tools used to crack open nuts by chimpanzees or capuchin monkeys are,” she writes in an e-mail. Seagulls dropping shellfish onto hard surfaces to crack them or lab rats pushing levers to get rewards would join tuskfish in the category of proto-tool—but not true tool—users.
Brown acknowledges that exactly what constitutes tool use is controversial. But he argues that it’s not logical to apply the same rules to fish as to primates or birds. For one thing, fish don’t have anything but their mouths to manipulate tools with, and for another, water poses different physical limitations than air. “One of the problems with the definition of tool use as it currently stands is it’s totally written for primates,” he says. “You cannot swing a hammer effectively underwater.”