Species such as humpbacks and blue whales are capable of travelling thousands of miles without feeding. Although whales are widespread, most species prefer the colder waters of the northern and southern hemispheres, and migrate to the equator to give birth. Whales produce a great variety of vocalizations, notably the extended songs of the humpback whale. With streamlined fusiform bodies and two limbs that are modified into flippers, whales can travel at speeds of up to 20 knots, though they are not as flexible or agile as seals. They are warm-blooded, and have a layer of fat, or blubber, under the skin.
Some species, such as the sperm whale can stay underwater for up to 90 minutes They have blowholes (modified nostrils) located on top of their heads, through which air is taken in and expelled. Whales evolved from land-living mammals, and must regularly surface to breathe air, although they can remain under water for long periods of time. Some species, such as sperm whales, are particularly well adapted for diving to great depths to catch squid and other favoured prey. They also have such keen hearing-whether above or below the surface of the water-that some can survive even if they are blind.
Toothed whales, in contrast, have conical teeth adapted to catching fish or squid. Baleen whales also have a well developed sense of smell. Because their heads are enormous-making up as much as 40% of their total body mass-and they have throat pleats that enable then to expand their mouths, they are able to take huge quantities of water into their mouth at a time. Several whale species exhibit sexual dimorphism, in that the females are larger than males.īaleen whales have no teeth instead they have plates of baleen, fringe-like structures that enable them to expel the huge mouthfuls of water they take in, while retaining the krill and plankton they feed on. The sperm whale is the largest toothed predator on earth. Whales range in size from the 2.6 metres (8.5 ft) and 135 kilograms (298 lb) dwarf sperm whale to the 29.9 metres (98 ft) and 190 metric tons (210 short tons) blue whale, which is the largest known creature that has ever lived. Whales are fully aquatic, open-ocean creatures: they can feed, mate, give birth, suckle and raise their young at sea. Whales consist of eight extant families: Balaenopteridae (the rorquals), Balaenidae (right whales), Cetotheriidae (the pygmy right whale), Eschrichtiidae (the grey whale), Monodontidae (belugas and narwhals), Physeteridae (the sperm whale), Kogiidae (the dwarf and pygmy sperm whale), and Ziphiidae (the beaked whales). The two parvorders of whales, baleen whales (Mysticeti) and toothed whales (Odontoceti), are thought to have had their last common ancestor around 34 million years ago. Their closest non-cetacean living relatives are the hippopotamuses, from which they and other cetaceans diverged about 54 million years ago. Whales, dolphins and porpoises belong to the order Cetartiodactyla, which consists of even-toed ungulates. They are an informal grouping within the infraorder Cetacea, which usually excludes dolphins and porpoises.
Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. Superfamily Inioidea (South American river dolphins).Superfamily Platanistoidea (Indian river dolphins).Family Delphinidae (dolphins and porpoises).Superfamily Physeteroidea (sperm whales)Ĭladistically included but traditionally excluded taxa.