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Baleen

Baleen

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Baleen or whalebone is a filter-feeder system inside the mouths of baleen whale
Baleen whale
The Baleen whales, also called whalebone whales or great whales, form the Mysticeti, one of two suborders of the Cetacea . Baleen whales are characterized by having baleen plates for filtering food from water, rather than having teeth. This distinguishes them from the other suborder of cetaceans,...

s. 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
Krill
Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...

 are filtered by the baleen and remain as food source for the whale. Baleen is similar to bristles and is made of keratin
Keratin
Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...

, the same substance found in human fingernails and hair. Some whales, such as the bowhead whale
Bowhead Whale
The bowhead whale is a baleen whale of the right whale family Balaenidae in suborder Mysticeti. A stocky dark-colored whale without a dorsal fin, it can grow to in length. This thick-bodied species can weigh to , second only to the blue whale, although the bowhead's maximum length is less than...

, have longer baleen than others. Others whales, such as the gray whale
Gray Whale
The gray whale, Eschrichtius robustus, is a baleen whale that migrates between feeding and breeding grounds yearly. It reaches a length of about , a weight of , and lives 50–70 years. The common name of the whale comes from the gray patches and white mottling on its dark skin. Gray whales were...

, 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 m (1.6 to 11.5 ft) long, and weigh up to 90 kilograms (198.4 lb). Its hairy fringes are called baleen hair or whalebone-hair. They are also called baleen bristles, which in sei whale
Sei Whale
The sei whale , Balaenoptera borealis, is a baleen whale, the third-largest rorqual after the blue whale and the fin whale. It inhabits most oceans and adjoining seas, and prefers deep offshore waters. It avoids polar and tropical waters and semi-enclosed bodies of water...

s are highly calcified, calcification functioning to increase their stiffness. Baleen plates are broader at the gumline (base). The plates have been compared to sieve
Sieve
A sieve, or sifter, separates wanted elements from unwanted material using a woven screen such as a mesh or net. However, in cooking, especially with flour, a sifter is used to aerate the substance, among other things. A strainer is a type of sieve typically used to separate a solid from a liquid...

s or Venetian blinds.

Etymology


The word "baleen" derives from Early Modern English
Early Modern English
Early Modern English is the stage of the English language used from about the end of the Middle English period to 1650. Thus, the first edition of the King James Bible and the works of William Shakespeare both belong to the late phase of Early Modern English...

 word meaning "whale
Whale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...

". This in turn derives from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 balaena, related to the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 phalaina – both of these also mean "whale".

Evolution


The oldest true fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

s of baleen are only 15 million years old, but baleen rarely fossilizes, and scientists 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
Jaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...

 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
Dall's Porpoise
Dall's porpoise is a species of porpoise found on the North Pacific. It came to worldwide attention in the 1970s when it was disclosed for the first time to the public that salmon fishing trawls were killing a lot, thousands of Dall's porpoises and other cetaceans each year by accidentally...

 has. In fact, it resembles baleen closely at the microscopic level.

Curiously, 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 shoal
Shoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...

s of prey (such as krill
Krill
Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...

, copepod
Copepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...

s, small fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 and sometimes bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s 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
Corset
A corset is a garment worn to hold and shape the torso into a desired shape for aesthetic or medical purposes...

 stays
Bone (corsetry)
In corsetry, a bone is one of the rigid parts of a corset that forms its frame and gives it rigidity.-Purpose, history and materials:The purpose of the boning in a corset varies slightly from era to era....

. It was commonly used to crease paper
Paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....

; its flexibility kept it from damaging the paper. It was also occasionally used in cable-backed bow
Cable-backed bow
A cable-backed bow is a bow reinforced with a cable on the back. The cable is made from either animal, vegetable or synthetic fibers and is tightened to increase the strength of the bow. A cable will relieve tension stress from the back of the bow by raising its neutral plane: the border between...

s. Synthetic materials are now usually used for similar purposes, especially plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

 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.

As a habitat


Baleen serves as a habitat for some species from the gastropod families Pyropeltidae
Pyropeltidae
Pyropeltidae is a family of gastropods in the clade Vetigastropoda .This family has no subfamilies.- Genera :Genera in the family Pyropeltidae include:...

, Cocculinidae
Cocculinidae
Cocculinidae is a family of sea snails, deep-sea limpets, marine gastropod mollusks in the clade Cocculiniformia .- Genera :Genera within the family Cocculinidae include:...

, Osteopeltidae
Osteopeltidae
Osteopeltidae is a family of gastropods in the clade Vetigastropoda .This family has no subfamilies....

 and Neolepetopsidae
Neolepetopsidae
Neolepetopsidae is a family of gastropods in the clade Patellogastropoda .This family has no subfamilies.- Etymology :...

.