The red eared turtle's carapace averages 5-8 inches, with a record length of 11 inches. The turtle is named for a broad reddish (occasionally yellow) stripe or blotch behind each eye along the neck. The carapace is oval and flattened (especially in the male), has a weak keel that is more pronounced in the young, and the rear marginal scutes are notched. The first marginal scute extends beyond the suture between the first costal and the first vertebral scutes. The carapace usually consists of a dark green background with light and dark highly variable markings. The plastron is yellow with dark paired irregular markings in the center of most scutes. The plastron is highly variable, with some older individual's essentially dark with only a little remaining yellow. The head, legs, and tail are green with fine yellow irregular lines. Older males are sometimes so melanistic that the markings are lost. The lower jaw, when viewed from the front, is rounded, not flattened as with other similar turtles.