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Animal Database
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Animal Database
Not to be confused with: Phocides, Pholcidae, Phocoenidae
Phocidae
800px-Northern Elephant Seal, Piedras Blancas, San Simeon, CA 02feb2009
A Northern Elephant Seal
Scientific Classification
Kingdom Animalia
Phylum Chordata
Family Phocidae

Phocidae is a family consisting of true earless seals. It includes 18 extant species. A member of this family is also called a Phocid.

Phocidae consists of two subfamilies:

  • Monachinae, which consists of seals that inhabit the southern hemisphere, such as monk seals and leopard seals.
  • Phocinae, which consists of seals that inhabit the northern hemisphere, such as harp and harbor seals.

Range[]

They are found in the oceans of both hemispheres. They live mostly in polar, subpolar, and temperate climates, with the exception of the more tropical monk seals. Most species live in saltwater, but one species, the Baikal Seal lives in freshwater.

Characteristics[]

Adult phocids vary from 1.17 meters (3.8 ft) in length and 45 kilograms (99 lb) in weight in the ringed seal, to 4.9 meters (16 ft) and 2,400 kilograms (5,300 lb) in the southern elephant seal. 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 temperatures. 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, unlike other pinnipeds. They are more streamlined than fur seals and sea lions, so can 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.

Behaviour[]

While otariids are known for speed and maneuverability, phocids are known for efficient, economical movement. This allows most phocids to forage far from land to exploit prey resources, while otariids are tied to rich upwelling zones close to breeding sites. Phocids swim by sideways movements of their bodies, using their hind flippers to fullest effect. True seals do not communicate by "barking" like otariids. Instead, they communicate by slapping the water and grunting. Phocids spend most of their time at sea, although they return to land or pack ice to breed and give birth. Pregnant females spend long periods foraging at sea, building up fat reserves, and then return to the breeding site to use their stored energy to nurse pups. The common seal displays a reproductive strategy similar to that of otariids in which the mother makes short foraging trips between nursing bouts. Because a phocid mother's feeding grounds are often hundreds of kilometers from the breeding site, she must fast while lactating. This combination of fasting with lactation requires the mother to provide large amounts of energy to her pup at a time when she is not eating (and often, not drinking). Mothers must supply their own metabolic needs while nursing.

Taxonomy[]

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