The head tends to appear swollen behind the eyes and the lower jaw barely protrudes past the upper jaw. Coloration of the dorsum varies from pale gray to black. An irregular pattern of light blotches on the upper surface of specimen becoming darker on the sides and extending to the dark belly. During the breeding season A. texanum may appear paler and have more conspicuous light markings. A texanum has 14 to 16 costal grooves.
Males are smaller with longer and more compressed tails.
Larvae usually have light bars or crossbands on an olive green or dark brown background. The adult small-mouth salamander prefers to eat insects, slugs and worms. Reproduction Ambystoma texanum breeds very early in the year. The migration to breeding ponds seems to be stimulated by just a few days of rain in late winter, frequently while ice still covers portions of the ponds. They tend to stay closer to breeding ponds in summer and late winter than other salamander species.