In the video, an orange-dotted tuskfish digs a clam out of the sand, carries it over to a rock, and repeatedly throws the clam against the rock to crush it.
Tool use was once considered an exclusively human trait, but Jane Goodall's reports of tool use in chimpanzees in the 1960s changed that. Since then, many other animals have been observed using tools, including various primates, several kinds of birds, dolphins, elephants, and other animals.
The actions recorded in the video are remarkably similar to previous reports of tool use by fish. Every case has involved a species of wrasse using a rock as an anvil to crush shellfish and similar behavior was also reported in a sixbar wrasse in an aquarium setting.
Wrasses are one of the largest and most diverse families of marine fishes. Bernardi noted that several of the species observed using tools are not closely related, but cover a broad range of evolutionary history within the wrasse family. They are at opposite ends of the phylogenetic tree, so this may be a deep-seated behavioral trait in all wrasses.
very interesting. The animal excavates sand to get the shell out, then swims for a long time to find an appropriate area where it can crack the shell," Bernardi said. "It requires a lot of forward thinking, because there are a number of steps involved. For a fish, it's a pretty big deal."
Bernardi shot the video in Palau in 2009.