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Other whales, such as the gray whale, only use one side of their baleen. These baleen bristles are arranged in plates across the upper jaw of whales. Depending on the species, a baleen plate can be 0.5 to 3.5 m (1.6 to 11.5 ft) long, and weigh up to 90 kg (200 lb). Its hairy fringes are called baleen hair or whalebone hair.
The toothed whales (also called odontocetes, systematic name Odontoceti) are a clade of cetaceans that includes dolphins, porpoises, and all other whales with teeth, such as beaked whales and the sperm whales. 73 species of toothed whales are described.
The tooth was inscribed: "This is the tooth of a sperm whale that was caught near the Galápagos Islands by the crew of the ship Adam [of London], and made 100 barrels of oil in the year 1817." [5] Other sea animal ivories were used as alternatives to the rarer whale teeth.
The sperm whale has 18 to 26 teeth on each side of its lower jaw which fit into sockets in the upper jaw. [56] The teeth are cone-shaped and weigh up to 1 kilogram (2.2 lb) each. [57] The teeth are functional, but do not appear to be necessary for capturing or eating squid, as well-fed animals have been found without teeth or even with deformed ...
Baleen whales can have streamlined or large bodies, depending on the feeding behavior, and two limbs that are modified into flippers. The fin whale is the fastest baleen whale, recorded swimming at 10 m/s (36 km/h; 22 mph). Baleen whales use their baleen plates to filter out food from the water by either lunge-feeding or skim-feeding
Odontocetes, such as the sperm whale, possess teeth with cementum cells overlying dentine cells. Unlike human teeth, which are composed mostly of enamel on the portion of the tooth outside of the gum, whale teeth have cementum outside the gum. Only in larger whales, where the cementum is worn away on the tip of the tooth, does enamel show.
The common name was chosen because the part of the tooth that protrudes from the gums (unlike the strap-like teeth of strap-toothed whales) has a shape similar to the tip of a flensing spade as used by 19th-century whalers. Despite the rather similar dentition, the spade-toothed whale and strap-toothed whale seem to be only distantly related.
Skull of a cross between a narwhal and a beluga whale, at the Zoological Museum, Copenhagen. The beluga was first described in 1776 by Peter Simon Pallas. [1] It is a member of the family Monodontidae, which is in turn part of the parvorder Odontoceti (toothed whales). [1]