Lifestyle & Belief

Video shows fish using rock as a tool

Scientists have for the first time captured a fish using a tool on video, Discovery News reports. An orange-dotted tuskfish was spotted and recorded throwing a clam against a rock to break it open.

The moment was shot off the Pacific island of Palau in 2009 by Giacomo Bernardi, an evolutionary biologist at the University of California, Santa Cruz, and the finding was published in the journal Coral Reefs last week: individual C. anchorago was observed cracking bivalves using a rock as an anvil. After two such events, we started filming the behavior, which was repeated a third time (see Electronic Supplementary Material). Each event lasted less than 5 min, for a total observation time of approximately 20 min. The fish first dug out the bivalve by fanning sand with its pectoral fin and then took the mollusk to a rock, or coral head, where it was crushed in a similar way to what has been described for C. schoenleinii.

"What the movie shows is very interesting," Bernardi said in a statement, according to Discovery News. "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. It requires a lot of forward thinking, because there are a number of steps involved. For a fish, it's a pretty big deal."

The tuskfish is a kind of reef fish known as a wrasse, Live Science reports, and wrasses have been known to use rocks as tools before. But scientists have never had video proof until now.

"We don't spend that much time underwater observing fishes," Bernardi told Live Science. "It may be that all wrasses do this. It happens really quickly, so it would be easy to miss."