Hyenas, or hyaenas (from Ancient Greek ὕαινα, hýaina),[1] are feliform carnivoran mammals of the family Hyaenidae /haɪˈɛnɪdiː/. With only four extant species (each in its own genus), it is the fifth-smallest family in the Carnivora and one of the smallest in the class Mammalia.[2] Despite their low diversity, hyenas are unique and vital components of most African ecosystems.