External Morphological Description of Adult Tortoise (Testudo graeca graeca) and Terrapin (Trachemys scripta elegans)

Our study was focused on the external features differentiation of two adult species of turtles, including a land tortoise (Testudo graeca graeca) and a freshwater turtle (Trachemys scripta elegans), by gross morphological description of head, carapace, plastron, and tail. Generally, turtles show gross morphological differences according to the ecology and the environment. The carapace and legs are the fascinating noticeable parts showing significant differences between tortoise and turtle as T. graeca graeca shows a small carapace length with noticeable convexity. In contrast, the freshwater turtle has a flattened broad carapace adapted to swimming. At the same time, the legs of T. graeca show multiple keratinized spurs with rigid claws, but T. scripta has legs covered with soft, moist skin and thin claws. The plastron is relatively the same in both species, while the head is unique with a large size and red flap in T. scripta. We conclude that the flat body and legs with broad head are a modification for swimming, while the rigid claws with keratinized outer leg skin are signs of land walking adaptation.