American Mud and Musk Turtles: Kinosternidae

American mud and musk turtles have glands, or sacs, along their sides that produce a musky substance that smells like the spray of a skunk. The upper shell, or carapace (KARE-a-pays), is rather tall, giving each turtle the outline of half a flattened ball when viewed from the side. The lower shell, or plastron (PLAS-trun), looks different in separate species. In some species the plastron has one or two hinges reaching from the left to the right side of the shell, but in others the shell has no hinges. The hinges allow the plastron and carapace to pull tight against one another after the turtle pulls its head, neck, legs, and tail into the shell. Some mud and musk turtles have a plastron that covers only part of the lower body, while others have a quite large plastron that almost entirely conceals the undersides.

All of these small to medium-sized turtles have barbels (BAR-buhls), which are small bits of flesh that dangle from the chin. A few have very large heads. Most of the species in this family have a carapace that is less than 8 inches (20 centimeters) long and in some cases grows to just 4 inches (10 centimeters) in length. The largest species, called the Mexican giant musk turtle, has a carapace that reaches 15 inches (38 centimeters) long. Males and females look quite similar. Males, however, usually have thicker and longer tails that are tipped with a spine. Males also have two rough, scaly patches on each hind leg.