Chimps use rocks to crack open nuts, dolphins use sponges to scare up hidden fish, New Caledonian crows use sticks to fish for insects, certain octopuses—those Einsteins of the invertebrate world—use coconut shells as armor. Indeed tool use among mammals, birds and cephalopods is, by now, well documented. In recent years scientists have observed fish engaging in similarly brainy behavior on three occasions. Now Giacomo Bernardi of the University of California, Santa Cruz, has caught another fish in the act—and captured the behavior on video (below). This is apparently the first video documenting tool-use in a fish, and the fourth known example of the behavior in these animals. Bernardi observed the fish--an orange-dotted tuskfish (Choerodon anchorago), which is a type of wrasse--in shallow water off the coast of Palau. The animal dug up a clam from the sandy sea floor with its pectoral fin, carried the prize in its mouth some distance to a rocky area and then cracked it against the rock, using it as an anvil. The same individual carried out this task three times over a period of 20 minutes. This behavior, Bernardi said in a statement, "requires a lot of forward thinking, because there are a number of steps involved. For a fish, it's a pretty big deal." Bernardi describes his finding in the September 20 issue of Coral Reefs.
The views expressed are those of the author(s) and are not necessarily those of Scientific American.