Although the sharks may not actually be as big as the shark in the movie Jaws, new research shows that American alligators on the U.S. Atlantic and Gulf coasts do eat small sharks and stingrays. The study, published in the September 2017 issue of Southeastern Naturalist, is the first scientific documentation of a widespread interaction between the two predators.
James Nifong is a postdoctoral researcher with the Kansas Cooperative Fish and Wildlife Research Unit at Kansas State University, and study co-author.
Nifong said in a statement:
The frequency of one predator eating the other is really about size dynamics. 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.
Despite the freshwater and saltwater differences, it’s fairly common for sharks and rays to share the water with alligators. Many sharks and rays can swim into freshwater where opportunistic alligators can’t pass up a good meal. Although alligators don’t have salt glands like true crocodiles, they are resourceful as they travel between freshwater and marine habitats. Nifong said:
Alligators seek out fresh water in high-salinity environments. 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.
Although an alligator’s diet typically consists of crustaceans, snails and fish, alligators are opportunistic predators, Nifong said, so sharks may end up on the menu.
The researchers pumped the stomachs of more than 500 live and alert alligators to learn more about their diet. They also equipped the alligators with GPS transmitters to watch their movements and found that alligators travel between freshwater and estuaries – partially enclosed coastal water bodies where freshwater and salt water mix and house shark nurseries.
Nifong dug into history and found news reports from the late 1800s that described battles of large masses of sharks and alligators after flooding and high tides washed the predators together. One particular historical incident included in the journal article described how the sharks were attracted to blood from alligators feeding on fish. When the alligators were washed out to sea, the sharks attacked.
Bottom line: New research documents alligators eating sharks.
Eleanor Imster has helped write and edit EarthSky since 1995. She was an integral part of the award-winning EarthSky radio series almost since it began until it ended in 2013. Today, as Lead Editor at EarthSky.org, she helps present the science and nature stories and photos you enjoy. She also serves as one of the voices of EarthSky on social media platforms including Facebook, Twitter and G+. She and her husband live in Tennessee and have two grown sons.