Cetacea of any animal on earth, averaging and in mature males. The brain to body mass ratio in some odontocetes, such as belugas and narwhals, is second only to humans. In some whales, however, it is less than half that of humans: 0.9% versus 2.1%. The sperm whale ("Physeter macrocephalus") is the largest of all toothed predatory animals and possesses the largest brain. The cetacean skeleton is largely made up of cortical bone, which stabilizes the animal in the water. For this reason, the usual terrestrial compact bones, which are finely woven cancellous bone, are replaced with lighter and more elastic
Whale shark Whale shark The whale shark ("Rhincodon typus") is a slow-moving, filter-feeding carpet shark and the largest known extant fish species. The largest confirmed individual had a length of and a weight of about . The whale shark holds many records for size in the animal kingdom, most notably being by far the largest living nonmammalian vertebrate. It is the sole member of the genus Rhincodon and the only extant member of the family Rhincodontidae which belongs to the subclass Elasmobranchii in the class Chondrichthyes. Before 1984 it was classified as "Rhiniodon" into Rhinodontidae. The whale shark is found in open