In the mountain rivers live the otter and desman and in its waters the trout, anguillidae, the common minnows and some of the increasingly scarce autochthonous river crabs. The otter and the desman are two mammals with aquatic habits and very good swimmers. The otter feeds mainly on fish, while the desman seeks its food among the aquatic invertebrates that inhabit the riverbed. In lower sections of calmer waters swim barbel s and carps. Among the amphibians, the salamanders and as remarkable species: the Almanzor salamander (Salamandra salamandra almanzoris) and the Gredos toad (Bufo bufo gredosicola), which are two endemic subspecies to the Sistema Central.