This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Alligator snapping turtles look pretty intimidating. These massive, prehistoric-looking reptiles can reach more than 66 centimeters in length and weigh more than 100 kilograms. Add in their unusual ridged carapaces, finger-long claws and sharp, beaklike mouths and you've got an impressive package.
But in truth, alligator snapping turtles aren't all that aggressive. They tend to let their prey do the work by sitting passively still and letting fish swim into their wide-open mouths. "It's funny because in my experience the alligator snapping turtle is far more docile than its cousin, the common snapping turtle," says Travis Thomas, a scientist with the Florida Fish and Wildlife Conservation Commission (FWC). "That's not to say that a large alligator snapping turtle wouldn't inflict heavy damage if you offered him a hand, but in most cases they become fatigued and become calm once removed from the water. You just always have to remember to stay away from those powerful jaws."
Thomas has had occasion to pull many of these massive turtles from the water over the past few years as part of a study, published in the April 9 issue in Zootaxa, which has important implications for their conservation. The paper, by Thomas and researchers from four other institutions, finds that alligator snapping turtles are not one species but three genetically and morphologically distinct species that separated from one another millions of years ago. The previous taxonomic name Macrochelys temminckii has now been linked only to the turtles in the western part of the turtles' range, around the Mississippi and Mobile rivers. One of the new species, M. apalachicolae, is restricted to the Apalachicola River and other Panhandle rivers in western Florida. The other new species, M. suwanniensis, lives farther east, in and around the Suwanee River that flows through Florida and Georgia.
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Unfortunately the restricted ranges of these three characters make them each rarer than when they were considered a single species. It also makes them more vulnerable to future dangers. As Thomas explained in a press release from the University of Florida, where he was a student when this research began, a catastrophic chemical spill or other event on the Suwannee could wipe out the turtle residents there.
Beyond this potential risk, Thomas tells me that all three species face numerous current threats, such as habitat degradation, dredging and overharvesting for their meat. (The turtles are legally protected in some states and can't be traded internationally, but have no federal-level protection.) He and his fellow researchers also encountered several turtles that have swallowed fishing hooks and tackle, which he says could injure or kill them. "It's likely that these ingested hooks are from trotlines and limb lines or bush hooks, which are passively set and baited and left out overnight," he says. "Alligator snapping turtles are nocturnal and opportunistic scavengers, so they are out foraging at night and encountering these baited hooks. We are sure that alligator snapping turtles and other freshwater turtles are ingesting them; however, we are unsure of the effect. This is something we will want to look at in the near future."
The FWC has already conducted a three-year survey of the Suwanee population, which it estimated at fewer than 900 adults, a number that is actually higher than expected. Thomas reports that they will now begin an intensive survey of the four major rivers that M. apalachicolae inhabits in Florida. That project starts next week. "I hope other states will determine the status of their populations," he says. "I know Georgia has already conducted some good population work, and now it's important for us to reexamine the temminckii species status and distribution because we just reduced its range by naming the other species." He also hopes that all states with alligator snapping turtles will move to legally protect them throughout their ranges. (The Center for Biological Diversity petitioned in 2012 to have alligator snapping turtles protected under the U.S. Endangered Species Act.)
Thomas, who grew up on the Suwanee, plans to keep studying the massive turtles. "It's a great thrill," he says. "I consider it an honor to work with such magnificent creatures."
Photos © and courtesy of Travis Thomas
