Predator vs. Predator: New study finds alligators eat sharks

Kansas State University postdoctoral researcher James Nifong documents American alligators' widespread predation of four species of shark like this nurse shark. (Photo courtesy of U.S. Fish and Wildlife Service J.N. "Ding" Darling National Wildlife Refuge.)

MANHATTAN, Kansas — Alligators just stepped up their game in the battle for supreme badassery. Researchers have found the fearsome reptiles are feasting on more than just the everyday fish in their habitats — they're also chowing down on sharks.

Researchers at Kansas State University documented American alligators along the Gulf Coast and the Atlantic Coast, studying their diets amid research on freshwater river systems and food chain. The team pumped the stomachs of 500 alligators to learn more about their diet and tracked them with GPS devices. They were surprised to discover that the gators snacked on stingrays as well as sharks, though smaller species like nurse sharks, as opposed to larger great whites.

Kansas State University postdoctoral researcher James Nifong documents American alligators' widespread predation of four species of shark like this nurse shark. (Photo courtesy of U.S. Fish and Wildlife Service J.N. “Ding” Darling National Wildlife Refuge.)

“We documented alligators consuming three new species of sharks and one species of stingray,” says James Nifong, a postdoctoral researcher with the Kansas Cooperative Fish and Wildlife Research Unit, in a university news release. “Before this, there have only been a few observations from an island off the Georgia coast, but the new findings document the occurrence of these interactions from the Atlantic coast of Georgia around the Florida peninsula to the Gulf Coast and Florida panhandle.”

This was the first such documentation of widespread interaction between these two fearsome prehistoric predators.

Even though sharks don't live in freshwater, it's not uncommon for sharks and alligators to come in contact with each other in these regions. Nifong says that sharks often swim into the gators' freshwater habitats. And though alligators lacking the salt gland that crocodiles possess, they've shown the ability to thrive the moving between freshwater and salt water.

“Alligators seek out fresh water in high-salinity environments,” says Nifong. “When it rains really hard, they can actually sip fresh water off the surface of the salt water. That can prolong the time they can stay in a saltwater environment.”

So while alligators normally eat crustaceans and fish, it makes sense that they also can't resist easy prey in the form of a smaller, younger, or weakened shark.

“The frequency of one predator eating the other is really about size dynamic,” says Nifong. “If a small shark swims by an alligator and the alligator feels like it can take the shark down, it will.”

The research was published in the journal Southeastern Naturalist.