The American alligator (Alligator mississippiensis) is known to be a crafty and fierce predator that devours anything it can snare. However, given that the reptile lacks salt glands, scientists had always believed that its diet was restricted to the fish and crustaceans that dwell in its freshwater habitat. Now, a new study suggests that the opportunistic beasts also gobble down saltwater inhabitants like crabs, sea turtles, stingrays, and even sharks.
James Nifong, an ecologist at Kansas State University who has been studying the alligators’ diet for nine years, stumbled upon this discovery when he captured a female gator with a young Atlantic stingray in her jaws. Since then, he and wildlife biologist Russell Lowers have documented three separate instances of alligators preying on a lemon shark, a nurse shark, and a bonnethead shark. While the stingrays and sharks, which ranged from two-feet to four-feet long, were small, the researchers speculate that larger alligators might be attacking bigger sharks as well. Also, the preying is not a one-way street – sharks have been observed eating American alligators as well. Nifong says, “Both are known for their extreme eating habits, and both are highly opportunistic predators. So, when presented with a potential opportunity to feed, they are not likely to pass it up.”
The scientists say despite their different habitats, sharks and rays frequently share the water with alligators. The saltwater inhabitants often swim into the freshwater, while the reptiles are resourceful enough to survive in the brackish estuarine waters for short periods of time if a tasty morsel is in sight. According to Nifong, “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."
Adam Rosenblatt, an ecologist at the University of North Florida, believes the reason it took so long for researchers to discover the reptiles’ saltwater diet is that both alligators and sharks are hard to track and observe in the wild. Since the gators eat smaller sharks, their prey could also easily be mistaken for fish. The expert says it is also difficult to find evidence of sharks or stingrays in the reptiles’ stomachs because “most prey gators eat turn to mush pretty quickly within their stomachs. It all turns into one big pile of indistinguishable stuff, except for certain body parts like hair and shells.” Nifong, who has examined the guts of over 500 alligators and never found any evidence, agrees with this theory.
Though the gator’s dietary range is undoubtedly impressive, the study, published in the peer-reviewed journal Southeastern Naturalist in October 2017, unveils a more significant finding — the ecological impact of the reptiles’ regular trips between fresh and salty waters. Nifong says as they move between the two habitats, the gators help transport nutrients from the rich marine waters to the fresh waters. Since the phenomenon occurs in gator habitats across the US southeast, the researcher believes it has a big effect on estuarine food webs — information that is very helpful when planning for conservation efforts.
Resources: sciencenews.org,nationalgeographic.com, phys.org