Alligator snapping turtles are the only turtles in the world to have evolved an oral predatory lure. These turtles have a forked, vermiform (“worm-like”) fishing lure on the upper surface of their tongues. When a gator snapper detects nearby fish, the red-wigglerish bait, engorged with blood and buoyant in water, becomes erect and starts to twitch. Fish that stray too close to the open maw display are summarily snapped and swallowed.
These turtles are highly piscivorous, albeit indiscriminate predators, with a broad diet that also includes crayfish, freshwater mussels, salamanders, juvenile alligators, turtles, snakes (including Cottonmouths), wood ducks and carrion. They seldom take healthy game fish like large-mouth bass. Interestingly, they sometimes eat acorns, wild grapes, palmetto berries and other fruits that fall into the water.
Alligator snappers are especially fond of smaller turtles and frequently prey on musk turtles (Sternotherus spp.), which are often abundant in habitats where snappers occur. Alligator snappers can detect the odors of musk turtles in the water column, and musk turtles, in turn, are able to discern the presence of nearby gator snappers using chemical cues (and avoiding them, when possible!).
Legendary turtle ecologist Archie Carr (1909-1987), who spent time in Savannah as a youth, told a good alligator snapper story that involved the species preying on musk turtles.
At one point the Carr family became the proud owners of a confiscated, large male alligator snapper, a 100-pound behemoth brought to them from the Suwannee River community of Jasper, FL. “Jasper,” relocated to the Carr’s home near Micanopy, was initially placed in a small dugout pool where he quickly habituated to being hand-fed fish. Of his own volition, Jasper soon moved down slope to a natural lake behind the house, a wetland that contained Macrochelys prey in abundance. Although he continued to hustle shore-ward for the free meals the Carr’s regularly carried to the lake margin, he again became a wild turtle, a real predator. Archie wrote of the agonizing sounds that came from the lake on warm nights. Their windows open on mild evenings, Archie, lying in bed, would hear the “sickening, crunching noises” of Jasper dispatching musk turtles by cracking them in his jaws.
Using the oral lure, alligator snappers may adopt a quintessential sit-and-wait foraging mode. Some turtles have been reported to be rather sedentary, ensconced in the same lair for weeks, letting supper come to them so to speak. But commonly individuals are active foragers–bottom-walkers who hunt at night.