What are Reptiles?
Reptiles of the southeastern U.S. are vertebrates of the taxonomic class Reptilia including animals such as snakes and lizards (order Squamata), turtles and tortoises (order Testudines), and crocodilians (order Crocodilia). Commonly called "cold-blooded," reptiles are ectotherms, meaning they are unable to regulate their own body temperature and are instead influenced by the temperature of their surroundings. Reptiles are characterized by skin with scales or horned plates and commonly reproduce by laying eggs, although some types of snakes bear live young. In Alabama, Kentucky, Mississippi, and Tennessee, reptiles are represented by the three taxonomic orders listed below.

Southeastern Species of Greatest Conservation Need Learn more about regional reptile species of greatest conservation need by browsing our species information Web application.

	Crocodilians (order Crocodilia) Crocodilians include animals such as alligators and crocodiles. There is one family within this order in the region.
	Snakes and Lizards (order Squamata) Squamates include animals such as snakes and lizards. There are nine families in within this order in the region.
	Tortoises and Turtles (order Testudines) Tortoises and Turtles include animals such as terrapins, sea turtles, and pond turtles. There are seven families within this order in the region.

Ecological Importance of Reptiles
Reptiles play an important role in ecosystems as both consumers and as prey items. For example, snakes and other reptiles consume many small mammals and invertebrates, helping to balance these populations in the ecosystem. Reptiles can regulate plant growth as well. Aquatic turtles play a crucial role in regulating growth of aquatic plants, contributing to healthier aquatic ecosystems (NOAA Southwest Fisheries Science Center, 2006). Reptiles such as snakes, lizards, and turtles are a food source for many larger predators. Reptiles such as alligators and snapping turtles will consume other reptiles, including their own species (Fuller & Somma, 2002).

Reptiles of the Southeastern United States
The southern states harbor the greatest diversity of reptiles in the U.S. In the Southeast, turtle species diversity is higher than anywhere else in the nation, along with a type of lizard called skinks that prefer the Southeast's abundant moisture (Stein, Kutner, & Adams, 2000). Water snakes of the genus Nerodia are found only in the states east of Texas. While mammalian and amphibian species diversity increases in mountainous areas, reptile species diversity is highest in the Mississippi Valley, an area lacking widespread variations in elevation (Stein et al., 2000).

Within Alabama, Mississippi, Kentucky, and Tennessee, reptile species number as follows: in Alabama, there are 85 species with one endemic species; in Mississippi, there are 82 species with one endemic species; in Tennessee, there are 58 species but no endemic species; in Kentucky, there are 53 species but no endemic species (Stein et al., 2000).

For more about reptiles of Alabama, Mississippi, Kentucky, and Tennessee, refer to the NBII catalog query for reptiles on our "Reptile Web Resources" page.