Great White Sharks Binge on Dead Whales
When these predators feast on blubber they may even meet mates.
Contrary to popular legend, including the film Jaws, great white sharks aren't solitary hunters after all. When the apex predators catch a dead whale's scent, they converge on the buffet.
Scientists witnessed this unexpected behavior in South Africa's False Bay, where four whales died of natural causes over the course of a decade. In winter, great whites hunt the 60,000 Cape fur seals foraging around an island rookery there. But when a whale dies, the seals get a break while up to 40 sharks a day devour the behemoth instead.
"White sharks are known as these killing machines, but they probably depend a lot on scavenging, especially as they get older," says Neil Hammerschlag, a University of Miami marine ecologist and coauthor of the study, published in PLOS ONE.
During one episode, as seven great whites simultaneously tore blubber from a Bryde's whale, one was so intent on the fatty meal that it chomped down on its neighbor's head, leaving two teeth behind. Unfazed, both sharks kept eating.
Researchers watching from a boat noted that sharks are picky eaters, mouthing the carcass before settling on a specific spot to attack. What's more, there's a pecking order: The largest predators, which can exceed 15 feet, dominate blubber-rich areas.
Still, the oldest, biggest sharks are rarely seen in the bay (they may be too large to catch fast-swimming seals) except when a dead whale lures them in for a shared meal. The event may also provide an opportunity to meet potential mates.
After the sharks are finished eating and the carcass sinks to the seafloor, a bevy of creatures, from crabs to microscopic worms, feast on the leftovers.
This story originally ran in the September-October 2013 issue as "Stuffed to the Gills."