Porpoises produce ultrasonic clicks, which are used for both navigation ( echolocation) and social communication. Calves are typically born in the spring and summer months and remain dependent on the female until the following spring. Females may get one calf every year under favourable conditions. Little is known about reproductive behaviour. Porpoises feed largely on fish and squid, much like the rest of the odontocetes. Porpoises are abundant and found in a multitude of environments, including rivers ( finless porpoise), coastal and shelf waters ( harbour porpoise, vaquita) and open ocean ( Dall's porpoise and spectacled porpoise), covering all water temperatures from tropical ( Sea of Cortez, vaquita) to polar ( Greenland, harbour porpoise).
#Porpoise vs dolphin skin
As all cetaceans, they have a layer of fat, or blubber, under the skin to keep them warm in cold water. Some species are well adapted for diving to great depths. Porpoises use echolocation as their primary sensory system. They have streamlined bodies and two limbs that are modified into flippers. Several species exhibit sexual dimorphism in that the females are larger than males. Porpoises range in size from the vaquita, at 1.4 metres (4 feet 7 inches) in length and 54 kilograms (119 pounds) in weight, to the Dall's porpoise, at 2.3 m (7 ft 7 in) and 220 kg (490 lb). The cetaceans' closest living relatives are the hippopotamuses, having diverged from them about 40 million years ago. Porpoises, and other cetaceans, belong to the clade Cetartiodactyla with even-toed ungulates. Hector's dolphin) also lack a pronounced beak. Porpoises are distinguished from dolphins by their flattened, spade-shaped teeth distinct from the conical teeth of dolphins, and lack of a pronounced beak, although some dolphins (e.g. There are eight extant species of porpoise, all among the smallest of the toothed whales. They are, however, more closely related to narwhals and belugas than to the true dolphins. Porpoises are a group of fully aquatic marine mammals, similar in appearance to a dolphin, all of which are classified under the family Phocoenidae, parvorder Odontoceti (toothed whales).
0 kommentar(er)
