This means that E. sosorum has the smallest habitat of any vertebrate in the world. The average length of the Barton Springs salamander is 6.35 cm. Dorsal color varies in life from dark through medium gray to purplish gray or gray-brown to yellowish brown to yellowish cream. Overall, the mottled pattern gives the salamander olive brown specks with a base color of yellowish cream. The presence of silvery-white iridophores enhances the salamanders' luster.
Some salamanders appear pale due to the lack of melanophores.
The trunk of E. sosorum is finely speckled with melanophores while the ventral surface is creamy to translucent in color. Sometimes the stomach contents, as well as the presence of eggs in females, can be seen through the translucent skin. Dorsally, the limbs of E. sosorum , are unevenly speckled as well as the toes. Ventrally, the limbs are not speckled. In addition the relatively short tail of E. sosorum has an uneven distribution of melanophores.