The largest freshwater turtle in North America is the Alligator Snapping Turtle, Macroclemys temminckii, often locally called the Loggerhead Turtle (not to be confused with the Loggerhead sea turtle that is common along Louisiana’s coast).
This species is brown, has three rows of large pointed scutes down the back, a very long tail, and a massive head that cannot be entirely drawn into the shell. Overall, it looks like a rough stump in the water.
These turtles can grow very large - over 100 pounds, the largest being 219 pounds - and are very powerful. Undoubtedly, a very large specimen could sever a finger if bitten at the joint. The good news is that they do not generally lash out to bite; rather they sit with mouth open and bite if something is ignorantly placed inside. This is due to their well known behavior of attracting a meal. As mentioned before, they resemble a log or stump on the bottom of the water body. The head has little appendages all over the surface that break the outline of a turtle head. They gape the mouth, and wiggle a little pink piece of flesh that resembles a worm moving. As a fish approaches to eat the worm, the turtle takes a bite. Therefore, when one sees one of these turtles with its mouth agape, never, never, never point to the inside with a finger!!!
Alligator Snappers rarely leave the water, though they occasionally sun a little. If they leave, they are usually going to lay up to about 50 round leathery eggs. They are, however, very good climbers.
Distinguishing from the Common Snapping Turtle: The Alligator Snapping Turtle is has the three keels down the back of the shell (vs. usually smoother on the back), defensively sitss with the mouth open (vs. typically strikes viciously in defense), has four supramarginal scales (between the marginals and costals) (vs. having the marginals and costals touching), has a strongly hooked beak (vs. lacking a hooked beak), and moves about with great difficulty (vs. moving about easily and with some speed).
Handling an Alligator Snapping Turtle: Since the turtle is quite heavy, it cannot be picked up by its tail (it would separate its vertebrae). Since it cannot pull its head all the way under the shell, the turtle cannot bite a hand that is placed under the shell over its head. Therefore, to carry an adult Alligator Snapper, one should place one hand above the turtle’s head and under its shell, and the other hand above the turtle’s tail and under its shell, and carry it like a box. Be careful of sharp toenails!