Baleen is a filter-feeder system inside the mouths of baleen whales.
The baleen system works by a whale opening its mouth underwater and
taking in water. The whale then pushes the water out, and animals such
as krill are filtered by the baleen and remain as food source for the
Baleen is similar to bristles and consists of keratin, the same
substance found in human fingernails and hair.
Baleen is a skin
derivative. Some whales, such as the bowhead whale, have longer baleen
than others. 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 the whale.
As a material for various human uses, baleen is usually called
whalebone. It is not to be confused (but often is) with whale bone or
whale's bone meaning the actual bones of whales, used in carving, for
cutlery handles and other uses for the bones of various large species.
Like other bone materials, this often functioned as a substitute for
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.
3 Filter feeding
4 Human uses
5 As a habitat
6 See also
8 Further reading
9 External links
The word "baleen" derives from the Latin bālaena, related to the
Greek phalaina – both of which mean "whale".
The oldest true fossils of baleen are only 15 million years old
because 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 beneath the eyes, and
loose lower jaw bones at the chin.
Baleen is believed to have evolved
around 30 million years ago, possibly from a hard, gummy upper jaw,
like the one a
Dall's porpoise has; it closely resembles baleen at the
microscopic level. The initial evolution and radiation of baleen
plates is believed to have occurred during Early
Antarctica broke off from
Gondwana and the Antarctic Circumpolar
Current was formed, increasing productivity of ocean environments.
This occurred because the current kept warm ocean waters away from the
area that is now Antarctica, producing steep gradients in temperature,
salinity, light, and nutrients, where the warm water meets the
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. However, developing mysticetes do not
produce tooth enamel because at some point this trait evolved to
become a pseudogene. This is likely to have occurred about 28 million
years ago and proves that dentition is an ancestral state of
mysticetes. Using parsimony to study this and other ancestral
characters suggest that the common ancestor of aetiocetids and
edentulous mysticetes evolved lateral nutrient foramina, which are
believed to have provided blood vessels and nerves a way to reach
developing baleen. Further research suggests that the baleen of
Aetiocetus was arranged in bundles between widely spaced teeth. If
true, this combination of baleen and dentition in
Aetiocetus would act
as a transition state between odontocetes and mysticetes. This
intermediate step is further supported by evidence of other changes
that occurred with the evolution of baleen that make it possible for
the organisms to survive using filter feeding, such as a change in
skull structure and throat elasticity. It would be highly unlikely for
all of these changes to occur at once. Therefore, it is proposed that
Oligocene aetiocetids possess both ancestral and descendent character
states regarding feeding strategies. This makes them mosaic taxa,
showing that either baleen evolved before dentition was lost or that
the traits for filter feeding originally evolved for other functions.
It also shows that the evolution could have occurred gradually because
the ancestral state was originally maintained. Therefore, the mosaic
whales could have exploited new resources using filter feeding while
not abandoning their previous prey strategies. The result of this
stepwise transition is apparent in modern-day baleen whales, because
of their enamel pseudogenes and their in utero development and
reabsorbing of teeth.
If it is true that many early baleen whales also had teeth, 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). Intense research has been carried out to sort out
the evolution and phylogenetic history of mysticetes, but much debate
surrounds this issue.
Iñupiat baleen basket, with an ivory handle, made by Kinguktuk
(1871–1941) of Barrow, Alaska, displayed at the Museum of Man, San
A whale's baleen plates play the most important role in its
filter-feeding process. 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
People formerly used baleen (usually referred to as "whalebone") for
making numerous items where flexibility and strength were required,
including backscratchers, collar stiffeners, buggy whips, parasol
ribs, crinoline petticoats, and 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
As a habitat
Baleen serves as a habitat for some species from the gastropod
families Pyropeltidae, Cocculinidae, Osteopeltidae, and
John Henry Devereux, a South Carolina architect who used whale jaw
bones to adorn the largest mansion on Sullivan's Island
^ Fudge, Douglas S.; Szewciw, Lawrence J.; Schwalb, Astrid N. (2009).
"Morphology and Development of Blue Whale Baleen: An Annotated
Translation of Tycho Tullberg's Classic 1883 Paper" (PDF). Aquatic
Mammals. 35 (2): 226–52.
doi:10.1578/AM.35.2.2009.226. [permanent dead link]
^ Szewciw, L. J.; De Kerckhove, D. G.; Grime, G. W.; Fudge, D. S.
Calcification provides mechanical reinforcement to whale
baleen -keratin" (PDF). Proceedings of the Royal Society B: Biological
Sciences. 277 (1694): 2597–605. doi:10.1098/rspb.2010.0399.
PMC 2982044 . PMID 20392736. Archived from the original
(PDF) on 2011-12-25.
^ a b Deméré, Thomas; Michael R. McGowen; Annalisa Berta; John
Gatesy (September 2007). "Morphological and Molecular Evidence for a
Stepwise Evolutionary Transition from Teeth to
Baleen in Mysticete
Whales". Systematic Biology. 57 (1): 15–37.
doi:10.1080/10635150701884632. PMID 18266181. Retrieved November
^ Marx, Felix G. (19 February 2010). "Climate, critters and cetaceans:
cenozoic drivers of the evolution of modern whales". Science. 327
(5968): 993–996. Bibcode:2010Sci...327..993M.
^ Fitzgerald, Erich M.G. (15 August 2006). "A bizarre new toothed
mysticete (Cetacea) from Australia and the early evolution of baleen
whales". Proceedings of the Royal Society B: Biological Sciences. 273:
^ McLean, James H. (2008). "Three New Species of the Family
Neolepetopsidae (Patellogastropoda) from Hydrothermal Vents and Whale
Falls in the Northeastern Pacific". Journal of Shellfish Research. 27:
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):
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.
Lay summary – Thoughtomics (March 16, 2011).
Wikimedia Commons has media related to Baleen.
"Whalebone". New International Encyclopedia. 1905.
Institute of Cetacean Research
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Australia (Western Australia)