Earless seal

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The true seals or earless seals are one of the three main groups of mammals within the seal superfamily, Pinnipedia. All true seals are members of the family Phocidae (pronounced /ˈfoʊsədiː/). They are sometimes called crawling seals to distinguish them from the fur seals and sea lions of the family Otariidae. Seals live in the oceans of both hemispheres and are mostly confined to polar, sub-polar, and temperate climates, with the exception of the more tropical monk seals.

Contents

Anatomy

Adult phocids vary from 1.17 meters (4 ft) in length and 45 kilograms (99 lb) in weight, in the Ringed Seal, to 4.9 meters (16 ft) and 2,400 kilograms (5,291 lb) in the Southern Elephant Seal.[2]

Phocids are more specialized for aquatic life than otariids. They lack external ears and have sleek, streamlined bodies. Retractable nipples, internal testicles and an internal penis sheath provide further streamlining. A smooth layer of blubber lies underneath the skin. Phocids are able to divert blood-flow to this layer to help control their temperature.

Limbs

Their fore-flippers are used primarily for steering, while their hind flippers are bound to the pelvis in such a way that they cannot bring them under their body to walk on them.

They are more streamlined than fur seals and sea lions and can therefore swim more effectively over long distances. However, because they cannot turn their hind flippers downward, they are very clumsy on land, having to wriggle with their front flippers and abdominal muscles.

Phocids have fewer teeth than land-based members of the Carnivora, although they retain powerful canines. Some species lack molars altogether. The dental formula is: Upper: 2-3.1.4.0-2, lower: 1-2.1.4.0-2

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