Class: Mammalia
Subclass: Eutheria
Order: Cetacea
Whales are a diverse group of marine mammals that have evolved to living a life exclusively in marine ocean environments. They belong to the order cetacea, which also include dolphins and porpoises. Though usually dolphins and porpoises tend to not be classified with whales.
The defining characteristics of whales is their relatively large size compared with other cetaceans like dolphins and orcas(killer whales). Though there are some exceptions like the pygmy sperm whale at 3.5m which looks like it's larger species.
A breaching humpback whale. image: wikipedia
Whales are typically divided into two groups:
- toothed whales (Odontoceti ) and;
- baleen- filter feeders (Mysticeti )
Wikipedia notes:
Whale (origin Old English hwæl from Proto-Germanic *hwalaz) 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 the suborder Odontoceti (toothed whales). This suborder includes the sperm whale, killer whale, pilot whale, and beluga whale.
The other Cetacean suborder, Mysticeti (baleen whales), comprises filter feeders that eat small organisms, such as krill, caught by straining seawater through a comblike structure found in the mouth called baleen. This suborder includes the blue whale, the humpback whale, the bowhead whale and the minke whale.
All cetaceans have forelimbs modified as fins, a tail with horizontal flukes, and nasal openings (blowholes) on top of the head.
Parts of a blue whale. image: wikipedia
Whales range in size from the blue whale, the largest animal known to have ever existed at 30 m and 180 tonnes, to pygmy species such as the pygmy sperm whale at 3.5 m .
Whales inhabit all the world's oceans and number in the millions, with annual population growth rate estimates for various species ranging from 3% to 13%.
Whales are long-lived, humpback whales living for up to 77 years, while bowhead whales may live for over a century.
Human hunting of whales from the 17th century until 1986 radically reduced the populations of some whale species.
Whales play a role in creation myths, for example among the Inuit, and are revered by coastal people in countries such as Ghana and Vietnam.
Source: reference
Whale. (2014, November 18). In Wikipedia, The Free Encyclopedia. Retrieved 21:25, November 23, 2014, from http://en.wikipedia.org/w/index.php?title=Whale&oldid=634300021