Toothed whale porpoise as a fish. Toothed whales, as well as baleen whales, are descendants of land-dwelling mammals of the artiodactyl order (even-toed ungulates). They are closely related to the hippopotamus, sharing a common ancestor that lived around 54 million years ago (mya). The primitive cetaceans, or archaeocetes, first took to the sea approximately 49 mya and became fully aquatic by 5–10 million years later. The adaptation of echolocation and enhanced fat synthesis in blubber occurred when toothed whales split apart from baleen whales, and distinguishes modern toothed whales from fully aquatic archaeocetes. This happened around 34 mya. Unlike toothed whales, baleen
Strap-toothed whale individual was seen breaching between the South Orkney Islands and South Georgia. Strap-toothed whales' diet consists primarily of squid, although research has suggested that a small portion of their diet may also consist of fish or crustaceans. Adult males have a gape half the size of females and juveniles, limiting their squid to those weighing and less. Nothing is known about social organization of this species. This species has never been hunted or entangled in fishing gear. It is believed to be in a rather safe position compared with other mesoplodonts. Layard's beaked whale is included in the Memorandum of