RAZOR-BACKED MUSK TURTLE (Sternotherus carinatus), (GRAY, 1856)
IDENTIFICATION: 4-7 inches (10-17.6 cm) The grayish brown to tan carapace is oval in dorsal perspective. In lateral perspective the carapace is highly domed with each side sharply sloping at an angle from the keeled mid-line of the carapace. The plastron varies in coloration from yellowish to brown. A weakly developed plastral hinge is present in younger specimens but may be relatively absent among older specimens as the fleshy areas between the plastral scutes increases with age. A gular scute is absent from the plastron. The flesh between the plastral elements ranges in color from that of the rest of the fleshy parts to having a suffusion of orange or pink. Olive to dark spots are present on the head and tail. Small vertical streaks are present on the tan colored cusp of the mouth. Two barbels are present on the chin.
GEOGRAPHIC DISTRIBUTION: Razor-backed musk turtles occupy a geographic range that includes south central Mississippi to the Gulf of Mexico, southeastern Oklahoma and central Arkansas southward to eastern and central Texas .
BEHAVIOR AND ECOLOGY: This small turtle inhabits bodies of freshwater with soft bottoms and aquatic vegetation and can be found in streams that have slow moving and swift currents. Populations from southern localities may remain active throughout most of the year. Females usually lay between 2-5 elliptical brittle-shelled eggs per clutch.
This species is primarily aquatic but spends a considerable amount of time basking amid logs and the emergent branches of trees that have fallen in the water. In spite of the penchant for basking, some specimens may bear healthy growth of algae on their shells. Razor-back musk turtles are primarily carnivorous consuming a wide range of crustaceans, insects, mollusk, amphibians, carrion and some aquatic vegetation. These small turtles are susceptible to various predators ranging from predatory diving beetles, (Family Dytiscidae), fish, water snakes (Nerodia sp.) (Ernst and Lovich, 2009), alligator snapping turtles (Macrochelys temminckii) and American alligators (Alligator mississippiensis) (Franklin, unpublished data). However, humans are responsible for more casualties than all of the other predators combined. Whenever hooked by a fisherman this species is sometimes killed. Razorback musk turtles are very alert and will dive back into the water at the slightest disturbance or hint of threat. Because of this anyone wishing to spot one of these turtles basking will have better luck first surveying potential basking sites with binoculars. A private keeper maintained a captive specimen for 29 years and 4 months.
