The Texas River Cooter is a relatively large turtle, capable of growing to a shell length of 12+ inches (30.5 cm). They are green in color, with yellow and black markings that fade with age. Males can be distinguished from females by their longer tails, longer claws, and overall smaller size.
The Red-eared slider (Trachemys scripta elegans) shares its range and habits, but can easily be distinguished from the Texas Cooter by red patches on either side of its head. Various species of map turtle can also look much like juvenile Texas Cooters.