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From Wikipedia, the free encyclopedia

Baleen whales[1]
Fossil range: latest Eocene - Recent
Humpback Whale breaching
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Suborder: Mysticeti
Cope, 1891
Families

Balaenidae
Balaenopteridae
Eschrichtiidae
Neobalaenidae
Janjucetidae

Diversity
Around 15 species
Baleen

The baleen whales, also called whalebone whales or great whales, form the Mysticeti, one of two suborders of the Cetacea (whales, dolphins, and porpoises). 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, the toothed whales or Odontoceti. Living Mysticeti species have teeth only during the embryonal phase. Fossil Mysticeti had teeth before baleen evolved.

The suborder contains four families and fourteen species.

Contents

Etymology

The taxonomic name Mysticeti apparently derives from a transmission error in early copies of Aristotle's Historia Animalium in which "ο μυς το κητος" ("the whale known as 'the mouse' or 'Gutter whale' ") was mistakenly run together as "ο μυστικητος" ("the Mysticetus").[2] An alternate name for the suborder is Mystacoceti (from Greek μυσταξ "moustache" + κητος "whale").[3]

Anatomy

Baleen whales are generally larger than toothed whales, and females are bigger than males. This group includes the largest known animal species, the Blue Whale.

Baleen whales have two blowholes, causing a V-shaped blow.

Ecology and life history

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Behavioral ecology

Solitary or in small groups.

Breaching

In spite of their enormous size, baleen whales are able to leap completely out of the water. They can grow to 190,000 kilograms (420,000 lb) in weight and 33.5 metres (110 ft) in length.[4] Particularly known for its acrobatics is the Humpback Whale, but other baleen whales also break through the water surface with their body or beat it loudly with their fins. Some believe that the male baleen whales try to show off to the females, to increase their mating success. Scientists speculate that baleen whales and other cetaceans may engage in breaching to dislodge parasites, or scratch irritated skin. Breaching, and other behaviors like lobtailing, are also used to stun or kill nearby fish or krill.

Importance to humans

From the 11th to the late 20th centuries, baleen whales were hunted commercially for their oil and baleen. Their oil was used to make margarine and cooking oils, whilst their baleen was used to stiffen corsets, as parasol ribs and to crease paper.

Evolutionary history

Parietobalaena palmeri skull

Early baleen whales first appeared as far back as Early Oligocene, or perhaps the latest Eocene (39-29 million years ago; e.g. Llanocetus). Early baleen whales possessed teeth inherited from their ancestors, as opposed to baleen, in modern species. The Oligocene species Aetiocetus cotylalveus is considered the evolutionary link between toothed and baleen whales. It was discovered by renowned fossil collector Douglas Emlong in 1964 near Seal Rock State Recreation Site, Oregon, in a sandstone formation.[5] In the early 1990s, the species Janjucetus hunderi was discovered in Victoria, Australia by a surfer and was described in 2006 by E. M. G. Fitzgerald.[6] Janjucetus was a baleen whale with sharp teeth that hunted fish and squid as well as larger prey, potentially including sharks and dolphin-like cetaceans. These fossils hint that early baleen whales were predatory and eventually evolved into the gentler, toothless whales known today. A recent study identified palatal foramina (bony impressions of blood vessels that 'feed' the baleen racks) in the palate of a toothed mysticete, Aetiocetus weltoni. The scientists involved indicated that this discovery implies that this whale possessed both teeth and baleen, and serves as an intermediate adaptive role between primitive toothed mysticetes and more advanced toothless mysticetes.[7] The first baleen-bearing, toothless baleen whales (such as Eomysticetus, and Micromysticetus) appeared in the late Oligocene.[8] Early baleen whales probably could not echolocate; no anatomical evidence preserved in the skulls and ear regions of any fossil baleen whales show any of the adaptations associated with echolocation as in 'toothed whales' (Odontoceti).[6]

Taxonomic classification

†Extinct

The earliest baleen whale found is called Llanocetus Denticrenatus and it was found on Seymour Island, Antarctica, by Dr. Mitchell in 1989. The species was around in the late eocene, about 45 mya.

References

  1. ^ Mead, James G. and Robert L. Brownell, Jr (November 16, 2005). Wilson, D. E., and Reeder, D. M. (eds). ed. Mammal Species of the World (3rd edition ed.). Johns Hopkins University Press. pp. 723–743. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3/browse.asp?id=14300002. 
  2. ^ OED 'mysticete' (n, 1)
  3. ^ OED 'mystacocete'
  4. ^ Dewey, T.; Fox, D. (2002). "Balaenoptera musculus (On-line)". Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Balaenoptera_musculus.html. Retrieved 2009-06-13. 
  5. ^ Wallace, D. R. (2007). Neptune's Ark: From Ichthyosaurs to Orcas. Berkeley ; London: University of California Press. ISBN 0-520-24322-6. 
  6. ^ a b Fitzgerald, E. M. G. (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 (1604): 2955–2963. doi:10.1098/rspb.2006.3664. 
  7. ^ Deméré, T., McGowen, M., Berta, A., Gatesy, J. (2008). Morphological and Molecular Evidence for a Stepwise Evolutionary Transition from Teeth to Baleen in Mysticete Whales. Systematic Biology, 57(1), 15-37.
  8. ^ A. E. Sanders and L. G. Barnes. 2002. Paleontology of the Late Oligocene Ashley and Chandler Bridge Formations of South Carolina, 3: Eomysticetidae, a new family of primitive mysticetes (Mammalia: Cetacea). Smithsonian Contributions to Paleobiology 93:313-356.

Simple English

Baleen whales
Fossil range: latest Eocene - Recent
File:Humpback stellwagen
Humpback Whale breaching
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Suborder: Mysticeti
Cope, 1891
Diversity
Around 15 species, see below.
Families

Balaenidae
Balaenopteridae
Eschrichtiidae
Neobalaenidae
Janjucetidae†

[[File:|thumb|Baleen]] The baleen whales, also called whalebone whales or great whales, make up the Mysticeti, one of the two groups of the Cetacea (whales, dolphins, and porpoises).

Baleen whales have baleen plates for filtering food from water, instead of having teeth. This makes them different from the other group of cetaceans, the toothed whales or Odontoceti. Living Mysticeti species have teeth only when they are still in the mothers' womb. Mysticeti had teeth before baleen whales appeared, according to fossils.

The suborder contains four families and fourteen species. The scientific name derives from the Greek word mystidos, which means "unknowable".

Contents

Anatomy

Baleen whales are generally larger than toothed whales, and females are larger than males. This group includes the largest living animal species, the Blue Whale.

Baleen whales have two blowholes, so they will have a V-shaped blow.

Baleen

Baleen whales do not have teeth. Instead, they have baleen, which look like a curtain of long plates hanging down from the top of the whale's mouth.[1] Those plates might be 12 feet long, and a foot or more wide. Looking at them from the outside, they look like straight knives hanging down, but from the inside, they are bristly, like a big toothbrush.[1]

A baleen whale uses its baleen to eat. It sucks water into its mouth through the baleen. This keeps out the bigger creatures in the water, letting only smaller plankton and other creatures into the mouth.[1] Then, the tongue is used to push the water back out. Since the inside of the baleen is bristly, the small creatures inside the mouth are caught in the bristles, and they are swallowed.[1]

Breaching

Although they are very heavy, baleen whales are able to jump completely out of the water. Humpback Whales are known for their jumping skills, but other baleen whales also jump out from the water with their body or beat it loudly with their fins. Nobody knows for sure why the whales do this. Some people think that the male baleen whales try to show off to the females.

Importance to humans

From the 11th to the late 20th centuries, baleen whales were hunted for their oil and baleen. Their oil can be made into margarine and cooking oils. Baleen was used to stiffen corsets, as parasol ribs, and to crease paper.

References

Look up Mysticeti in Wikispecies, a directory of species
  1. 1.0 1.1 1.2 1.3 Fulbright, Jeannie K. (2006). Exploring Creation with Zoology 2: Swimming Creatures of the Fifth Day. 1106 Meridian Plaza, Suite 220, Anderson, IN 46016: Apologia Educational Ministries, Inc.. ISBN 1-932012-73-7. 


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