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.
- Enhanced statistical models will aid conservation...on January 17, 2022 at 2:30 pm
Retrieving an accurate picture of what a tagged animal does as it journeys through its environment requires statistical analysis, especially when it comes to animal movement, and the methods statisticians use are always evolving to make full use of the large and complex data sets that are available. A recent study by researchers at the Institute for the Oceans and Fisheries (IOF) and the UBC department of statistics has taken us a step closer to understanding the behaviours of northern resident […]
- Earth's first gianton December 23, 2021 at 7:30 pm
The two-meter skull of an enormous new ichthyosaur species, Earth's first known giant creature, reveals how both the extinct marine reptiles and modern whales became giants.
- After thousands of years, an iconic whale...on December 17, 2021 at 3:27 pm
The iconic tusked whale of the Arctic has a new enemy -- noise. A unique study shows that narwhals are highly affected by noise from ships and seismic airgun pulses -- even at 20-30 kilometers away. As ice melts, noise levels in the Arctic are rising, worrying scientists about the future of narwhals.
- Baleens read like a whale's history bookon December 8, 2021 at 5:33 pm
Chemically analyzing sequential samples from the baleen of dead whales makes it possible to read not only the history of the diet, but also the migration route of the animals. In a new study, researchers present their results of a novel way of analyzing nitrogen isotopes in animal tissue.
- Forty percent of North Atlantic right whale...on December 2, 2021 at 8:39 pm
A new study confirms that the Gulf of St. Lawrence is an important habitat for a large proportion of the endangered North Atlantic right whale population.
Phys.org - latest science and technology news stories Phys.org internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine.
- They live for a century and clean our rivers, but...on January 12, 2022 at 1:40 pm
Freshwater mussels are dying suddenly and in the thousands, with each mass death event bringing these endangered molluscs closer to extinction. Tragically, these events rarely get noticed.
- Dolphin females have working clitoris, anatomical...on January 10, 2022 at 4:00 pm
Like humans, female dolphins have a functional clitoris, according to a study appearing January 10 in the journal Current Biology. The findings are based on the discovery that the clitoris-like structure positioned in the vaginal entrance of bottlenose dolphins has lots of sensory nerves and erectile bodies.
- More than half of plastics in Mediterranean...on January 10, 2022 at 3:19 pm
Researchers have, for the first time, simulated both micro- and macroplastics accumulation in Mediterranean Marine Protected Areas (MPAs). They found that the majority of Mediterranean countries included in the study had at least one MPA where more than half of macroplastics originated elsewhere. The study, published in Frontiers in Marine Science, highlights the need for international collaboration on plastic pollution management in marine protected areas.
- Hitting the beach this summer? Here are some of...on January 4, 2022 at 1:53 pm
Australia has one of the longest coastlines in the world. And it's packed with life of all shapes and sizes—from lively dolphins leaping offshore, to tiny crabs scurrying into their holes.
- Australian icebreaker maps deepsea mountainon December 30, 2021 at 8:20 pm
The summit of an underwater mountain, higher than Mount Kosciuszko, has been mapped for the first time by the Australian icebreaker Research and Supply Vessel (RSV) Nuyina.
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