Turtles are reptiles of the order Testudines, characterized by a special shell developed mainly from their ribs. There are over 350 living species of turtles, tortoises and terrapins. They are found everywhere except Antarctica and in both fresh and salt water.  Around 60 species are found in the United States and around 30 species call Alabama home. Only XX species of turtle can be found in the central Alabama region housing Harmon Park. 

Turtle shells are made mostly of bone; the upper part is the domed carapace, and the underside is the plastron or belly-plate. Its outer surface is covered in scales made of keratin (the same material of hair, horns, and claws). Turtles are ectotherms , i.e.  "cold-blooded", meaning that their internal temperature varies with their direct environment. They are generally opportunistic omnivores, feeding mainly on plants and animals with limited movements. Although many turtles migrate short distances seasonally, sea turtles are the only reptiles that migrate long distances.