Wikipedia tells us this about whales :
Whales, derived from Proto-Germanic word hwæl, are a widely distributed and diverse group of fully aquatic marine mammals. They comprise the extant families Cetotheriidae (whose only living member is the pygmy right whale), Balaenopteridae (the rorquals), Balaenidae (right whales), Eschrichtiidae (the gray whale), Monodontidae (belugas and narwhals), Physeteridae (the sperm whale), Kogiidae (the dwarf and pygmy sperm whale), and Ziphiidae (the beaked whales).[1][2] There are 40 extant species of whales. The two suborders of whales, Mysticeti and Odontoceti, are thought to have split up around 34 million years ago.[3] Whales belong to the clade Cetartiodactyla and their closest living relative is the hippo having diverged about 40 million years ago.[4] Whales range in size from the 2.6 metres (8.5 ft) and 135 kilograms (298 lb) dwarf sperm whale to the 34 metres (112 ft) and 190 metric tons (210 short tons) blue whale, which is also the largest creature on earth. Several species exhibit sexual dimorphism, in that the females are larger than males. TBut I like whales because they are: