Baleen hair is attached to each baleen plate

Baleen or so called whalebone is a filter-feeder system inside the mouths of baleen whales. The baleen system works when a whale opens its mouth underwater and then water pours into the whale's mouth. The whale then pushes the water out, and animals such as krill are filtered by the baleen and remain as food source for the whale. Baleen is similar to bristles and is made of keratin, the same substance found in human fingernails and hair. Some whales, such as the bowhead whale, have longer baleen than others. Others 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 the whale.

Depending on the species, a baleen plate can be 0.5 to 3.5 metres (1.6 to 11 ft) long, and weigh up to 90 kilograms (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, calcification functioning to increase their stiffness.^[1][2] Baleen plates are broader at the gumline (base). The plates have been compared to sieves or Venetian blinds.

  Etymology

The word "baleen" derives from Early Modern English word meaning "whale". This in turn derives from the Latin balaena, related to the Greek phalaina – both of these also mean "whale".

  Evolution

The oldest true fossils of baleen are only 15 million years old, but baleen rarely fossilizes, and scientists^[who?] believe it originated considerably earlier than that. This is indicated by baleen-related skull modifications being found in fossils from considerably earlier, including a buttress of bone in the upper jaw beneath the eyes, and loose lower jaw bones at the chin. Baleen is believed to have evolved around thirty million years ago, possibly from a hard, gummy upper jaw, like the one a Dall's porpoise has. In fact, it resembles baleen closely at the microscopic level.

Many early baleen whales also had teeth, but these were probably used only peripherally, or perhaps not at all (again like Dall's porpoise, which catches squid and fish by gripping them against its hard upper jaw).

  Filter feeding

A whale's baleen plates play the most important role in its filter-feeding process. In order to feed, a baleen whale opens its mouth widely and scoops in dense shoals of prey (such as krill, copepods, small fish and sometimes birds that happen to be near the shoals), together with large volumes of water. It then partly shuts its mouth and presses its tongue against its upper jaw, forcing the water to pass out sideways through the baleen, thus sieving out the prey which it then swallows.

  Human uses

People formerly used baleen for making numerous items where flexibility and strength were required, including collar stiffeners, buggy whips and parasol ribs, and as corset stays. It was commonly used to crease paper; its flexibility kept it from damaging the paper. It was also occasionally used in cable-backed bows. Synthetic materials are now usually used for similar purposes, especially plastic and fibre glass. Baleen was frequently used in the 18th and early 19th centuries as the handle for silver punch or toddy ladles. It was chosen for this use because of its insulating qualities. Baleen plates are also used by indigenous people to create fine crafts.^{[citation needed]}

  As a habitat

Baleen serves as a habitat for some species from the gastropod families Pyropeltidae, Cocculinidae, Osteopeltidae and Neolepetopsidae.^[3]

  References

  Further reading

• St. Aubin, D. J.; Stinson, R. H.; Geraci, J. R. (1984). "Aspects of the structure and composition of baleen, and some effects of exposure to petroleum hydrocarbons". Canadian Journal of Zoology 62 (2): 193–8. DOI:10.1139/z84-032. 
• Meredith, Robert W.; Gatesy, John; Cheng, Joyce; Springer, Mark S. (2010). "Pseudogenization of the tooth gene enamelysin (MMP20) in the common ancestor of extant baleen whales". Proceedings of the Royal Society B: Biological Sciences 278 (1708): 993–1002. DOI:10.1098/rspb.2010.1280. PMC 3049022. PMID 20861053. //www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3049022. Lay summary – Thoughtomics (March 16, 2011). 

  See also

• John Henry Devereux South Carolina architect who used whale jaw bones to adorn the largest mansion on Sullivan's Island

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