A blackspot tuskfish off Australia has its mouth full as it carries a cockle to a nearby rock, against which the fish was seen repeatedly bashing the shellfish to get at the fleshy bits inside.
A recent study in the journal Coral Reefs says the picture—snapped at a depth of nearly 60 feet (18 meters) in Australia's Great Barrier Reef in 2006—is the first ever taken of a tool-using fish in the wild.
Professional diver Scott Gardner was just about out of air and swimming back to the surface when he heard an odd cracking sound nearby. Swimming over to investigate, he spotted the foot-long (30-centimeter-long) fish at work.
"When Scott showed me his photos, I said 'Wow, this is quite amazing,'" said study co-author Alison Jones, a coral ecologist at Central Queensland University in Rockhampton, Australia.
If tuskfish can use tools in the wild, then it's possible other fish species can too—and that could have broader implications for fisheries management, Jones said.
"If older fish are teaching younger fish these patterns of behavior, then by taking out all of the older"—and therefore bigger and more attractive to fishers—"fish, will the younger fish be less able to forage effectively?" Jones said. "That's one of the critical questions that this observation raises."
Not everyone agrees the shellfish-smashing fish is actually using a tool. "It's taken six years to publish this research, because reviewers argued back and forth about whether it was a true example of tool use or not," co-author Jones said.But that definition was based on human and primate behavior, says Jones and her team, and can't be applied to fish.
"We argue that tuskfish have a different type of intelligence that's evolved for their specific environment. ... They don't have hands, and they have resistance in the water, so you can't expect them to use a tool the way a primate would."
