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Cetacea (/ s ɪ ˈ t eɪ ʃ ə /; from Latin cetus 'whale', from Ancient Greek κῆτος 'huge fish, sea monster') [3] is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises.
Cetacea (/ s ɪ ˈ t eɪ ʃ ə /; from Latin cetus 'whale', from Ancient Greek κῆτος 'huge fish, sea monster') is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises.
The following is a list of currently existing (or, in the jargon of taxonomy) 'extant' species of the infraorder cetacea (for extinct cetacean species, see the list of extinct cetaceans). The list is organized taxonomically into parvorders, superfamilies when applicable, families, subfamilies when applicable, genus, and then species.
A southern right whale tail-sailing. To feed the newborn, whales, being aquatic, must squirt the milk into the mouth of the calf. Nursing can occur while the mother whale is in the vertical or horizontal position. While nursing in the vertical position, a mother whale may sometimes rest with her tail flukes remaining stationary above the water.
The other more common method is to travel close to the surface and parallel to it, and then jerk upwards at full speed with as few as 3 tail strokes to perform a breach. [5] [6] In all breaches the cetacean clears the water with the majority of its body at an acute angle, such as an average of 30° to the horizontal as recorded in sperm whales. [7]
Species of the infraorder Cetacea A phylogenetic tree showing the relationships among cetacean families. [1]The evolution of cetaceans is thought to have begun in the Indian subcontinent from even-toed ungulates (Artiodactyla) 50 million years ago (mya) and to have proceeded over a period of at least 15 million years. [2]
Nonetheless, drag powered swimmers still have powerful tails for producing lift, and the tails of river otters are 125% the size of the thoracolumbar series. So, using river otters as a model, Ambulocetus was a pelvic paddler—swimming with alternating beats of the hindlimbs (without engaging the forelimbs)—and also undulated (moved up and ...
They propel themselves through the water with powerful up-and-down movement of their tail which ends in a paddle-like fluke, using their flipper-shaped forelimbs to maneuver. While the majority of cetaceans live in marine environments, a small number reside solely in brackish water or fresh water .