Sternotherus is a genus of turtles in the family Kinosternidae including six species commonly known as musk turtles. The genus is endemic to North America, occurring in the eastern third of the US and southeast Ontario, Canada. Musk glands positioned near the bridge of the shell can produce foul smelling secretions when the turtles are threatened, although gentle handling does not normally provoke a response. Sternotherus are moderately small turtles, with the largest species in the genus, the razor-backed musk turtle, attaining a maximum of 17.6 cm. in shell length. The carapace is characteristically oval and domed, with most species having one or three keels on the back which may become smoother and obscure with age in some species. Musk turtles are generally drab in color, mostly black, gray, brown, olive, or ocher, which aid in camouflaging them in their natural habitats. The head is relatively large and stout, marked with spots, streaks, or strips. The plastron has only 10 or 11 scutes, as opposed to 12, a more common condition in North American turtles. The tail is short, with males having a horny claw like tip.
Sternotherus
Distinguishing characteristics between musk turtles (Sternotherus) and the closely related mud turtles (Kinosternon) include a smaller plastron with legs exposed vs. a large plastron with legs concealed and: A, pectoral scute squarish vs. triangular; B, hinges less developed vs. well developed; C, skin between plastron scutes.
Eastern musk turtle (Sternotherus odoratus), captive hatchling
Stripe-necked musk turtle (Sternotherus peltifer) captive hatchling
The Kinosternidae are a family of mostly small turtles that includes the mud turtles and musk turtles. The family contains 25 species within four genera, but taxonomic reclassification is an ongoing process, so many sources vary on the exact numbers of species and subspecies. They inhabit slow-moving bodies of water, often with soft, muddy bottoms and abundant vegetation.
Kinosternidae
Red-cheeked mud turtle, Kinosternon scorpioides cruentatum
Mississippi mud turtle, Kinosternon subrubrum hippocrepis
Lake Chapala mud turtle, Kinosternon hirtipes chapalaense