Great White Sharks Talking Through Their Tails

Great white sharks appear to have more complex social interactions than suggested by their reputation as the sea's most infamous predator, according to A. Peter Klimley, a marine animal behaviorist at the UC Davis Bodega Marine Laboratory. Competing for freshly killed seals off the coast of the South Farallon Islands, 30 miles west of San Francisco Bay, great white sharks slap their tails on the water surface apparently as a form of threatening communication to defend or steal the meal. The tail slap may communicate by surface sound, by the volume of water sprayed on a competing shark or by the physical display of brute force, Klimley says. The vigor and frequency of such encounters may help decide the winner, he says, citing several occasions when smaller sharks eventually fed exclusively on the prey carcass. "The white shark is not just a feeding machine," Klimley says. "Using surface-generated signals for communication, it's more like a whale than other sharks." Klimley's hypothesis is based on 98 tail slaps recorded on video by him and by researchers Peter Pyle and Scot Anderson from Point Reyes Bird Observatory. Klimley presented the paper at a recent international symposium at Bodega on the biology of the great white shark.