Polyphemus is a genus of water fleas, and the only genus in the family Polyphemidae. There are two species, P. exiguus and P. pediculus, although allopatric speciation has resulted in a number of cryptic species of P. pediculus. Polyphemus exiguus inhabits open zones in the Caspian Sea, while Polyphemus pediculus exists throughout the Holarctic....
