American alligators are frequently seen ambling around golf courses in Florida as players warily compete their rounds. But new research suggests the reptiles partake in a far more outlandish habit when away from the greens – eating sharks.

US researchers have documented instances of alligators preying upon small sharks along the Atlantic and Gulf coasts. A study, published in the journal Southeastern Naturalist, claims to be the first scientific study of the largely unseen struggle between the two feared predators.

“The frequency of one predator eating the other is really about size dynamic,” said James Nifong, a researcher at Kansas State University. “If a small shark swims by an alligator and the alligator feels like it can take the shark down, it will, but we also reviewed some old stories about larger sharks eating smaller alligators.”

Nifong and his colleagues spent nearly 10 years studying alligators along the Florida and Georgia coasts, typically using lamps at night to view their nocturnal hunting activities. More than 500 alligators were caught and had their stomachs pumped to see what they had consumed.

Alligators typically eat fish, crustaceans and snails, but Nifong’s research found evidence that they had consumed three species of shark and a type of stingray. The sharks measured 3-4ft.

By looking at the historical record, Nifong saw there was evidence of alligators tangling with sharks as far back as the 1870s, but the observations were limited to an island off the Georgia coast, including one episode in which sharks attacked a group of alligators that were feeding on fish.

The new research found that shark-eating alligators are in fact found along the Atlantic coast of Georgia and Florida, around to Florida’s Gulf coast.

Although sharks prefer salt water and alligators are fresh-water-dwelling, Nifong said that sharks and rays could swim into freshwater and GPS tracking of alligators demonstrated that the animals were opportunistic enough to take advantage.

“Alligators seek out fresh water in high-salinity environments,” Nifong said. “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.”

More research is required to discover if alligator attacks on sharks are increasing, but interactions may be influenced by coastal development that has pushed alligators out of their estuarine habitats. This has put pressure on alligator populations.

“The findings bring into question how important sharks and rays are to the alligator diet as well as the fatality of some the juvenile sharks when we think about population management of endangered species,” Nifong said.