Tree of Life
Plant Flower, Tree
Invertebrate Octopus, Ant, Bee, Butterfly, Spider, Lobster
Vertebrate Fish, Seahorse, Ray, Shark, Frog, Turtle, Tortoise, Dinosaur
Bird, Ostrich, Owl, Crow, Parrot
Mammal Bat, Rabbit, Giraffe, Camel, Horse, Elephant, Mammoth
Whale, Dolphin, Walrus, Seal, Polar Bear, Bear, Cat, Tiger, Lion, Dog, Wolf
Monkey, Chimpanzee, Human
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.
Dolphin ancestor's hearing was more like hoofed...
on May 15, 2019 at 12:54 pm
Paleontologists are looking into the evolutionary origins of the whistles and squeaks that dolphins and porpoises make -- part of the rare echolocation ability that allows them to effectively navigate their dark environment. […]
How whales defy the cancer odds: Good genes
on May 10, 2019 at 1:13 pm
Scientists have studied potential cancer suppression mechanisms in cetaceans, the mammalian group that includes whales, dolphins and porpoises. Biologists picked apart the genome of the humpback whale, as well as the genomes of nine other cetaceans, in order to determine how their cancer defenses are so effective. […]
Mysterious river dolphin helps crack the code of...
on April 19, 2019 at 1:40 pm
The Araguaian river dolphin of Brazil was thought to be solitary with little social structure that would require communication. But researchers have discovered the dolphins actually are social and can make hundreds of different sounds, a finding that could help uncover how communication evolved in marine mammals. […]
Ancient, four-legged whale with otter-like...
on April 4, 2019 at 3:44 pm
Cetaceans, the group including whales and dolphins, originated in south Asia more than 50 million years ago from a small, four-legged, hoofed ancestor. Now, researchers reporting the discovery of an ancient four-legged whale -- found in 42.6-million-year-old marine sediments along the coast of Peru -- have new insight into whales' evolution and their dispersal to other parts of the world. […]
Climate change is a threat to dolphins' survival
on April 1, 2019 at 3:58 pm
An unprecedented marine heatwave had long-lasting negative impacts on both survival and birth rates on the iconic dolphin population in Shark Bay, Western Australia. Researchers have now documented that climate change may have more far-reaching consequences for the conservation of marine mammals than previously thought. […]
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Activists petition court to halt Japan dolphin...
on May 17, 2019 at 10:33 am
Campaigners on Friday urged a court in Japan to halt so-called "drive hunting" of dolphins in the country as part of an unprecedented lawsuit that argues the practice violates Japanese law. […]
Dolphin ancestor's hearing was more like hoofed...
on May 15, 2019 at 7:47 am
Vanderbilt University paleontologists are looking into the evolutionary origins of the whistles and squeaks that dolphins and porpoises make—part of the rare echolocation ability that allows them to effectively navigate their dark environment. […]
Brazilian giant's comeback shows preservation and...
on May 14, 2019 at 6:04 am
Several meters long and weighing hundreds of kilograms, the Amazon's pirarucu was almost fished to extinction. But the creation of sustainable development reserves in Brazil has ensured the giant fish—and its indigenous hunters—are flourishing again. […]
Big Brother-style surveillance gives new insight...
on May 14, 2019 at 5:58 am
Scientists are deploying ultra-sensitive sensors in the Amazon to collect images and sounds of the rainforest's rich biodiversity in real time, in an effort to track preservation efforts. […]
Officials seek to open major spillway on...
on May 9, 2019 at 9:20 pm
Army Corps of Engineers officials in Louisiana aim to open a historic flood control structure above New Orleans on Tuesday for an unprecedented second time in one year. […]