Two-toed amphiumas are the most prominent in the Amphiumidae family and the longest salamander species in the United States, They have four vestigial legs that end in two toes; the number of toes is one of the primary differences between
Amphiuma means and its relatives, the
one-toed and
three-toed amphiumas. Additional genetic studies have been conducted on the three species; genetic distance estimates suggest that there is high levels of similarity between two-toed amphiumas and three-toed amphiumas, and much greater dissimilarity between the one-toed amphiuma and the two-toed amphiuma. The head is pointed and wedge-shaped, and the eyes are small. Adults retain a single gill slit on each side of the head. They are black, dark grey or dark brown in color. == Distribution and habitat ==