Portal:Cetaceans
Cetaceans evolved from land mammals that adapted to marine life about 50 million years ago. Over a period of a few millions of years during the Eocene, the cetaceans returned to the sea. Their body is fusiform (spindle-shaped), the forelimbs are modified into flippers, the tiny hindlimbs are vestigial and the tail has horizontal flukes. Cetaceans are nearly hairless, and are insulated by a thick layer of blubber.
Cetaceans inhabit all of the world's oceans, as well as some rivers in South America and Asia. Some species can be found across the globe.
Cetology is the branch of marine science associated with the study of cetaceans.
Whale song is the sound made by whales to communicate. The word "song" is used in particular to describe the pattern of regular and predictable sounds made by some species of whales (notably the humpback) in a way that is reminiscent of human singing.
The mechanisms used to produce sound vary from one family of cetaceans to another. Marine mammals, such as whales, dolphins, and porpoises, are much more dependent on sound for communication and sensation than land mammals are , as other senses are of limited effectiveness in water. Sight is limited for marine mammals because of the way water absorbs light. Smell is also limited, as molecules diffuse more slowly in water than air, which makes smelling less effective. In addition, the speed of sound in water is roughly four times that in the atmosphere at sea level. Because sea-mammals are so dependent on hearing to communicate and feed, environmentalists and cetologists are concerned that they are being harmed by the increased ambient noise in the world's oceans caused by ships and marine seismic surveys.
More on whale songs
2014
January
The clymene dolphin (Stenella clymene) became the first confirmed naturally occurring hybrid marine mammal species when DNA analysis showed it to be descended from the spinner dolphin and the striped dolphin. [1]
2009
February
- 10 February - Filipino fishermen have rescued around 200 melon-headed whales which were stranded in shallow waters off the coast of Bataan. Only three dolphins were reported to have died. more
January
- 24 January - The Cove, a feature-length film documenting the killing of dolphins in Taiji, Wakayama, wins the U.S. Audience Award at the 2009 Sundance Film Festival. more
- 22 January - A group of nearly 50 Sperm Whales beached on the northwest coast of the island of Tasmania in Australia. Only five were still alive by Friday afternoon. more
2008
September
- 23 September - Speculation is raised over whether an object washed up near Wellington, New Zealand could be ambergris; City Council spokesman Richard MacLean says this is unlikely. Read more...
- 17 September - A man in Trefriw, Wales pleads guilty to the uncertified selling of a Harbour Porpoise skull on eBay. Read more...
- 10 September - Australia and New Zealand announce a non-lethal whale research program to challenge Japan's whaling. Read more...
August
- 26 August - Findings from the controversial Japanese whaling research program suggest that a loss of Antarctic sea ice due to increased temperatures has lowered whales' food supply, causing an overall decline in blubber. Read more...
- 12 August - IUCN changes the conservation status of the Humpback Whale and Southern Right Whale to "least concern" due to the species' recovery. Read more...
- 1 August - Snubfin Dolphins are recorded on camera for the first time along the Australian coastline. Read more...
- ...the leading cause of death in North Atlantic Right Whales is injury sustained from colliding with ships.
- ...the Spade Toothed Whale is the rarest, and probably the most poorly known large mammalian species.
- ...the ear bone in cetaceans is fused to the walls of the bone cavity where the ear bones are, making hearing in air nearly impossible. Instead sound is transmitted through their jaws and skull bones.
- ...from its discovery by John Edward Gray in 1850 until a re-assessment in 1981, the Clymene Dolphin was regarded as sub-species of the Spinner Dolphin.
- ...the Australian Snubfin Dolphin (Orcaella heinsohni) is a recently recognised species of dolphin first described in 2005.
Subcategories of Cetaceans:
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The Fin Whale, at 27 metres long, is the second largest whale and animal after the Blue Whale. It is found in all the world's major oceans, and in waters ranging from the polar to the tropical. It is absent only from waters close to the ice pack at both the north and south poles and relatively small areas of water away from the large oceans.
More on Fin Whales
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