"True seals" in the family Phocidae lack external pinnae and have less mobility in the hind limbs than do "eared" seals in the family Otaridae. Harp Seals were once thought to be closely related to Harbour Seals in the genus Phoca, but are now recongized as a separate genus (Pagophilus) more closely related to Hooded Seals (Cystophora).