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Mysticeti
Humpback Whale
A Humpback Whale.
Scientific Classification
Kingdom Animalia
Phylum Chordata
Class Mammalia
Order Cetacea

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, the toothed whales or Odontoceti. Living species of Mysticeti have teeth only during the embryonal phase. Fossil Mysticeti had teeth before baleen evolved. The suborder contains four extant families and 15 species.

Characteristics

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. These whales are found solitary or in small groups called pods.

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 m (110 ft) in length.

Particularly known for its acrobatics is the humpback whale, but other baleen whales also break through the water surface with their bodies or beat it loudly with their fins. Some believe the male baleen whales try to show off in the presence of females to increase their mating success. Scientists speculate 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.

Evolution

Early baleen whales first appeared as far back as the 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. This species was discovered by fossil collector Douglas Emlong in 1964 near Seal Rock State Recreation Site, Oregon, in a sandstone formation. 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. 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 the 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 this discovery implies this whale previously possessed both teeth and baleen, and serves as an intermediate adaptive role between primitive, toothed mysticetes and more advanced, toothless mysticetes. The first baleen-bearing, toothless baleen whales (such as Eomysticetus and Micromysticetus) appeared in the late Oligocene. 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.

Taxonomy

Suborder Mysticeti

Family †Aetiocetidae

† Aetiocetus
 A. cotylalveus
 A. polydentatus
 A. tomitai
 A. weltoni
† Ashorocetus
 A. eguchii
† Chonecetus
 C. sookensis
 C. goedertorum
† Morawanocetus
 M. yabukii
† Willungacetus
 W. aldingensis

Family †Aglaocetidae

† Aglaocetus
† Isanacetus
† Pinocetus

Family Balaenidae

Balaena
 B. mysticetus - Bowhead Whale
†Balaenella
†Balaenotus
†Balaenula
 B. balaenopsis
Eubalaena
 E. australis – Southern Right Whale
 †E. belgica
 E. glacialis – North Atlantic Right Whale 
 E. japonica – North Pacific Right Whale 
 †E. shinshuensis
†Eucetites
†Morenocetus

Family Balaenopteridae

†Archaebalaenoptera
Balaenoptera
 Balaenoptera acutorostrata - Common Minke Whale
 Balaenoptera bonaerensis - Southern Minke Whale
 Balaenoptera borealis - Sei Whale
 Balaenoptera brydei - Bryde's Whale
 Balaenoptera edeni - Eden's Whale
 Balaenoptera musculus - Blue Whale
 Balaenoptera omurai - Omura's Whale
 Balaenoptera physalus - Fin Whale
†Cetotheriophanes
†Diunatans
 D. luctoretemergo 
†Mauicetus
Megaptera
 M. novaeangliae – Humpback Whale
†Notiocetus
†Parabalaenoptera
 P. baulinensis
†Plesiobalaenoptera
†Praemegaptera
†Protororqualus

Family Cetotheriidae

†Cephalotropis
†Cetotherium
 C. capellinii
 C. crassangulum
 C. furlongi 
 C. incertum
 C. maicopicum
 C. mayeri
 C. parvum
 C. polyporum
 C. priscum
 C. pusillum
 C. rathkii
†Herpetocetus
†Hibacetus
†Joumocetus
 J. shimizui
†Metopocetus
†Mixocetus
†Nannocetus
Caperea
 C. marginata - Pygmy Right Whale
†Palaeobalaena
†Piscobalaena
 Piscobalaena nana
†Plesiocetopsis
†Titanocetus

†Family Cetotheriopsidae

†Cetotheriopsis
†Micromysticetus

†Family Diorocetidae

†Amphicetus
†Diorocetus
†Plesiocetus
†Thinocetus
†Uranocetus

†Family Eomysticetidae

†Eomysticetus

Family Eschrichtiidae

†Archaeschrichtius
†Eschrichtioides
Eschrichtius
 E. robustus – Gray Whale
†Gricetoides
†Megapteropsis

†Family Llanocetidae

†Llanocetus

†Family Mammalodontidae

†Janjucetus
 Janjucetus hunderi
†Mammalodon
 Mammalodon colliveri

†Family Pelocetidae

†Cophocetus
†Halicetus
†Parietobalaena
 P. affinis
 P. campiniana
 P. laxata
 P. palmeri
 P. securis
 P. yamaokai
†Pelocetus
†Eobalaenoptera
 E. harrisoni

incertae sedis

†Amphitera
†Burtinopsis
†Idiocetus
†Imerocetus
†Isocetus
†Mesocetus
†Mioceta
†Otradnocetus
†Peripolocetus
†Piscocetus
†Siphonocetus
†Tiphyocetus
†Tretulias
†Ulias

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