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.
Marine charities net more than iconic fishery:...
on March 8, 2018 at 1:55 pm
Massachusetts boasts one of the most iconic fisheries in the US, but new research suggests that protecting marine coastlines has surpassed commercial fishing as an economic driver. The study is the first to calculate the economic value of coastal preservation in Massachusetts. The research finds these efforts contributed $179 million to the state's economy in 2014, more than finfish landings ($105 million) and whale-watching ($111 million). […]
Voice control: Why North Atlantic right whales...
on February 27, 2018 at 2:05 pm
Through extensive listening and analysis of whale calls -- which were recorded by a large collaboration of scientists over the past two decades -- researchers were able to pick up the slow gradual changes in sound production in the marine giants as they age. Looking at spectrograms of the calls, which provide visual representations of the sound, the research team could see the progression of vocal characteristics of the animals from calf throughout adulthood. […]
Beluga whales dive deeper, longer to find food in...
on February 20, 2018 at 9:12 pm
Beluga whales that spend summers feeding in the Arctic are diving deeper and longer to find food than in earlier years, when sea ice covered more of the ocean for longer periods, according to a new analysis. […]
Noise from ships scares porpoises
on February 20, 2018 at 7:34 pm
Porpoises communicate with each other using sounds. Therefore, they are highly sensitive to noise, such as ship noise. A new study shows that porpoises flee from and stop feeding when disturbed by heavy ship noise. […]
Monitoring bacteria on whale skin
on February 14, 2018 at 7:58 pm
Just like with humans, the skin on marine mammals serves as an important line of defense against pathogens in their environment. A new study sheds light on the skin microbiome -- a group of microorganisms that live on skin -- in healthy humpback whales, which could aid in future efforts to monitor their health. […]