dolphin : any of various small marine toothed whales (family Delphinidae) with the snout more or less elongated into a beak and the neck vertebrae partially fused
Note: While not closely related, dolphins and porpoises share a physical resemblance that often leads to misidentification. Dolphins typically have cone-shaped teeth, curved dorsal fins, and elongated beaks with large mouths, while porpoises have flat, spade-shaped teeth, triangular dorsal fins, and shortened beaks with smaller mouths. — Webster
Dolphins are a widely distributed and diverse group of aquatic mammals. They are an informal grouping within the order Cetacea, excluding whales and porpoises, so to zoologists the grouping is paraphyletic. The dolphins comprise the extant families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the new world river dolphins), and Pontoporiidae (the brackish dolphins), and the extinct Lipotidae (baiji or Chinese river dolphin). There are 40 extant species of dolphins. Dolphins, alongside other cetaceans, belong to the clade Cetartiodactyla with even-toed ungulates. Their closest living relatives are the hippopotamuses, having diverged about 40 million years ago.
Dolphins range in size from the 1.7 m (5.6 ft) long and 50 kg (110 lb) Maui’s dolphin to the 9.5 m (31 ft) and 10 t (11 short tons) killer whale. Several species exhibit sexual dimorphism, in that the males are larger than females. They have streamlined bodies and two limbs that are modified into flippers. Though not quite as flexible as seals, some dolphins can travel at 55.5 km/h (34.5 mph). Dolphins use their conical shaped teeth to capture fast moving prey. They have well-developed hearing which is adapted for both air and water and is so well developed that some can survive even if they are blind. Some species are well adapted for diving to great depths. They have a layer of fat, or blubber, under the skin to keep warm in the cold water.
Although dolphins are widespread, most species prefer the warmer waters of the tropic zones, but some, like the right whale dolphin, prefer colder climates. Dolphins feed largely on fish and squid, but a few, like the killer whale, feed on large mammals, like seals. Male dolphins typically mate with multiple females every year, but females only mate every two to three years. Calves are typically born in the spring and summer months and females bear all the responsibility for raising them. Mothers of some species fast and nurse their young for a relatively long period of time. Dolphins produce a variety of vocalizations, usually in the form of clicks and whistles. — Wikipedia
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Dolphins and Whales News -- ScienceDaily Whales and dolphins. Whale songs, beaching, endangered status -- current research news on all cetaceans.
- Plesiosaur fossils found in the Sahara suggest...on July 27, 2022 at 3:07 pm
Fossils of small plesiosaurs, long-necked marine reptiles from the age of dinosaurs, have been found in a 100-million year old river system that is now Morocco's Sahara Desert. This discovery suggests some species of plesiosaur, traditionally thought to be sea creatures, may have lived in freshwater.
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Whale sharks are filter feeders and have long been observed eating krill at Western Australia's Ningaloo Reef. But when researchers analysed biopsy samples from whale sharks at the reef, they discovered the animals were actually eating a lot of plant material. The finding makes whale sharks -- which have been reported up to 18m long -- the world's largest omnivore.
- Major dolphin DNA studyon July 12, 2022 at 2:26 pm
The first widespread census of the genetic diversity of common dolphin (Delphinus delphis) populations living along 3000km of Australia's southern coastline has raised key pointers for future conservation efforts. The comprehensive study calls for more conservation and policy efforts to preserve adaptive DNA diversity and assist connectivity between these dolphin groups. This will support long-term gene flow and adaptation during ongoing habitat changes -- including oceanic conditions affected […]
- Bomb detectors picking up more blue whale songs...on July 11, 2022 at 3:18 pm
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- 150 southern fin whales observed feeding togetheron July 7, 2022 at 6:18 pm
After blue whales, fin whales are the largest whales in the world -- and human beings have hunted both species to near-extinction. After the ban on commercial whaling in 1976, the stocks of these long-lived, but slow-growing creatures are rebounding: researchers have witnessed large groups of up to 150 southern fin whales in their historical feeding areas -- more than has ever been documented before using modern methods. Given these whales' key role in nutrient recycling, other species in the […]
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- Whales have altered their development to be able...on August 11, 2022 at 2:54 pm
Researchers found that different groups of whales and dolphins take varying routes as they develop in a delicate balancing act between their evolutionary history and current environment.
- Dolphins form rare alliance near Bimini,...on August 11, 2022 at 12:40 pm
Dolphins are known to be good at maintaining relationships, but a new study suggests their gregarious nature may extend beyond their own social circles.
- New research using stable isotopes sheds light on...on August 9, 2022 at 8:40 pm
An international collaborative study involving researchers from Massey University, the University of Canterbury, NIWA, and Flinders University has analyzed the isotopic niche of 21 species of toothed whales in New Zealand.
- France to give vitamins to beluga stranded in the...on August 7, 2022 at 9:38 am
French authorities were preparing Saturday to give vitamins to a beluga whale that swam way up the Seine river, as they raced to save the malnourished creature, which has so far refused food.
- Health fears over Beluga whale spotted in...on August 4, 2022 at 11:38 am
A beluga whale that swam up France's Seine river appears to be underweight and officials are worried about its health, regional authorities said Thursday.
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