These are organized by a classification scheme developed exclusively for Cosma. More…
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
Dolphins and Whales News -- ScienceDaily Whales and dolphins. Whale songs, beaching, endangered status -- current research news on all cetaceans.
'Biological passport' to monitor Earth's largest...
on August 9, 2018 at 1:34 pm
Whale sharks, the world's largest fish, roam less than previously thought. This new study used stable isotope analysis to demonstrate that whale sharks feeding at three disparate sites in the Western Indian Ocean and Arabian Gulf rarely swim more than a few hundred kilometers north or south from these areas according to researchers. […]
Whales use song as sonar, psychologist proposes
on July 30, 2018 at 5:29 pm
A psychologist has proposed that humpback whales may use song for long-range sonar. It's the singing whale, not the listening whale who is doing most of the analysis. If correct, the model should change the direction of how we study whales. […]
Satellite tracking reveals Philippine waters are...
on July 24, 2018 at 3:00 pm
A new scientific study has tracked juvenile whale sharks across the Philippines emphasizing the importance of the archipelago for the species. The study is the most complete tracking study of whale sharks in the country, with satellite tags deployed on different individuals in multiple sites. […]
Novel approach studies whale shark ages the best...
on July 18, 2018 at 2:47 pm
A new study of whale sharks, using a novel approach to gathering data, shows these endangered animals can live longer and grow larger than previously believed. […]
The freediving champions of the dolphin world
on July 17, 2018 at 1:48 pm
New research explains how some populations of bottlenose dolphins can dive to almost 1,000 meters while avoiding decompression sickness. The new hypothesis suggests that lung architecture and the management of blood flow allow bottlenose dolphins to access oxygen in the lungs while preventing uptake of nitrogen which would cause the bends. The findings act as a starting point to understand how environmental changes and anthropogenic interaction may impact the future of the species. […]