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.
New Zealand has its own population of blue whales
on May 17, 2018 at 3:38 pm
A group of blue whales that frequent the South Taranaki Bight (STB) between the North and South islands of New Zealand appears to be part of a local population that is genetically distinct from other blue whales in the Pacific Ocean and Southern Ocean, a new study has found. […]
Diverse and abundant megafauna documented at new...
on May 16, 2018 at 9:22 pm
Airborne marine biologists were dazzled by the diversity and abundance of large, unusual and sometimes endangered marine wildlife on a recent trip to the Northeast Canyons and Seamounts National Marine Monument, about 150 miles southeast of Cape Cod. […]
Jurassic fossil tail tells of missing link in...
on May 11, 2018 at 4:32 pm
A 180-million-year-old fossil has shed light on how some ancient crocodiles evolved into dolphin-like animals. […]
Ancient skull shows early 'baleen whale' had teeth
on May 10, 2018 at 7:02 pm
Today's baleen whales (Mysticetes) support their massive bodies by filtering huge volumes of small prey from seawater using comb-like baleen in their mouths. But new evidence based on careful analysis of a 34-million-year-old whale skull from Antarctica -- the second-oldest 'baleen' whale ever found -- suggests that early whales actually didn't have baleen. Their had well-developed gums and teeth, which they apparently used to bite large prey. […]
River dolphins are declining steeply in the...
on May 2, 2018 at 7:34 pm
Populations of freshwater dolphins in the Amazon basin are in steep decline, dropping by half about every decade at current rates, according to a new study. […]