Whale Bone

Baleens, also referred to as "Baleen plates", are triangular sheets of keratin that make up a filter-feeding system (the "Baleen rack") inside the mouth of baleen whales. The feeding process starts as the animal opens its mouth to take in water. The whale then pushes the water out through a rack of baleen plates, so as to retain (filter) what will serve as food for the whale. A baleen is similar to a bristle and consists of keratin, the same substance found in human fingernails, skin and hair. Some whales, such as the bowhead whale, have baleen of differing lengths. 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. They are also called baleen bristles, which in sei whales are highly calcified, with calcification functioning to increase their stiffness. Baleen plates are broader at the gumline (base). The plates have been compared to sieves or Venetian blinds. As a material for various human uses, baleen is usually called whalebone, which is a misnomer.