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They may be numerous, with some dolphins bearing over 100 teeth in their jaws. At the other extreme are the narwhals with their single long tusks and the almost toothless beaked whales with tusk-like teeth only in males. [20] In most beaked whales the teeth are seen to erupt in the lower jaw, and primarily occurs at the males sexual maturity. [21]
The family Balaenidae, the right whales, contains two genera and four species. All right whales have no ventral grooves; a distinctive head shape with a strongly arched, narrow rostrum, bowed lower jaw; lower lips that enfold the sides and front of the rostrum; and long, narrow, elastic baleen plates (up to nine times longer than wide) with fine baleen fringes.
Articles relating to the toothed whales (odontocetes, parvorder Odontocetiare), a parvorder of cetaceans that includes dolphins, porpoises, and all other whales possessing teeth, such as the beaked whales and the sperm whales. 73 species of toothed whales are described.
The transition from teeth to baleen is proposed to have occurred stepwise, from teeth to a hybrid to baleen. It is known that modern mysticetes have teeth initially and then develop baleen plate germs in utero , but lose their dentition and have only baleen during their juvenile years and adulthood.
The degree of calcification varies between species, with the sei whale having 14.5% hydroxyapatite, a mineral that coats teeth and bones, whereas minke whales have 1–4% hydroxyapatite. In most mammals, keratin structures, such as wool , air-dry, but aquatic whales rely on calcium salts to form on the plates to stiffen them. [ 58 ]
When the whale is submerged, it can close the blowhole, and air that passes through the phonic lips can circulate back to the lungs. The sperm whale, unlike other odontocetes, has only one pair of phonic lips, whereas all other toothed whales have two, [107] and it is located at the front of the nose instead of behind the melon.
Now, sperm whales are protected under the Marine Mammal Protection Act. So, in order to sell the animal's tooth, it must be over 100 years old, and the owner has to know where it's been since the ...
The largest Perrin's beaked whale calf, LACM 088901, at 2.45 m of length, appeared to be independent from its mother. The smallest specimen, USNM 504259, at 2.1 m of length, had a fringed tongue which indicated it was still suckling. [4] Teeth were not present in the immature specimen [verification needed], but are not needed for feeding.