What is "toothed whale"

Toothed \Toothed\, a.

1. Having teeth; furnished with teeth. ``Ruby-lipped and toothed with pearl.''
   --Herrick.

2. (Bot. & Zo["o]l.) Having marginal projecting points; dentate.

   Toothed whale (Zo["o]l.), any whale of the order Denticete. See Denticete.

   Toothed wheel, a wheel with teeth or projections cut or set on its edge or circumference, for transmitting motion by their action on the engaging teeth of another wheel.

n. (context marine biology English) A whale of the Odontoceti suborder of the cetaceans, including sperm whales, beaked whales, dolphins, and others.

n. any of several whales having simple conical teeth and feeding on fish etc.

The toothed whales ( systematic name Odontoceti) form a parvorder of the infraorder Cetacea, including sperm whales, beaked whales, dolphins, and porpoises. As the name suggests, the parvorder is characterized by the presence of teeth rather than the baleen of other whales. Seventy-three species of toothed whales are described. They are thought to have split from baleen whales, parvorder Mysticeti, around 34 million years ago (mya). Whales and dolphins, the paraphyletic groups of Cetacea, as well as porpoises, belong to the clade Cetartiodactyla with even-toed ungulates; their closest living relatives are the hippopotamuses which diverged about 40 mya.

Toothed whales range in size from the and vaquita to the and sperm whale. Several species of odontocetes exhibit sexual dimorphism, in that the females are larger than males. They have streamlined bodies and two limbs that are modified into flippers. Some can travel at up to 20 knots. Odontocetes have conical teeth designed for catching fish or squid. They have well-developed hearing, that is well adapted for both air and water, so much so that some can survive even if they are blind. Some species are well adapted for diving to great depths. Almost all have a layer of fat, or blubber, under the skin to keep warm in the cold water, with the exception of river dolphins.

Toothed whales consist of some of the most widespread mammals, but some, as with the vaquita, are restricted to certain areas. Odontocetes feed largely on fish and squid, but a few, like the killer whale, feed on mammals, such as pinnipeds. Males typically mate with multiple females every year, but females only mate every two to three years, making them polygynous. Calves are typically born in the spring and summer, and females bear the responsibility for raising them, but more sociable species rely on the family group to care for calves. Many species, mainly dolphins, are highly sociable, with some pods reaching over a thousand individuals.

Once hunted for their products, cetaceans are now protected by international law. Some species are attributed with high levels of intelligence. At the 2012 meeting of the American Association for the Advancement of Science, support was reiterated for a cetacean bill of rights, listing cetaceans as nonhuman persons. Besides whaling and drive hunting, they also face threats from bycatch and marine pollution. The baiji, for example, is considered functionally extinct by the IUCN, with the last sighting in 2004, due to heavy pollution to the Yangtze River. Whales occasionally feature in literature and film, as in the great white sperm whale of Herman Melville's Moby-Dick. Small odontocetes, mainly dolphins, are kept in captivity and trained to perform tricks. Whale watching has become a form of tourism around the world.