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
Whaling in Japan of extinction within a few decades according to IWC population estimates. In Japan, not only humpback, minke, and sperm whales, but many other smaller toothed whales, including species such as western gray, the endangered North Pacific right, and northern fin whales have been targets of illegal captures utilizing harpoons for dolphin hunts or intentionally drive whales into nets. Reports are later filed with administrative organs or research institutions as cases of "entanglements where fishermen tried their best to save whales". Products from internationally protected species' meat can also be found on markets even today mostly originating as "by-products" of entanglements,