Fur Seals and Sea Lions (Otariidae)
Fur Seals and Sea Lions (family Otariidae) constitute the eared seals.
Currently, Otariidae get classified into seven genera and sixteen different species:
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Types of Animals
- genus Arctocephalus
- genus Callorhinus
- genus Eumetopias
- genus Neophoca
- genus Otaria
- genus Phocarctos
- genus Zalophus
Stellar sea lions (Eumetopias jubatus), top picture, also called Northern sea lions, the largest eared seals, inhabit cold ocean water and rocky beaches typical of many areas of the West Coast from Northern California to Alaska.).
Males can grow over ten feet long and weigh well over a ton (2,000 pounds). Calling them Northern sea lions helps identify them as the cold water sea lions.
A dramatic population decline led to their being listed as a threatened species under the Endangered Species Act in 1990.California Sea Lion
The California Sea Lion (Zalophus californianus), a warm water marine mammal, breeds on coastal areas around California, in the warmer waters of the Pacific Ocean.
During nonbreeding season, they migrate as far nort as Alaska in search of food.
Social animals, they often congregate in large groups.
The IUCN lists one species, the Japanese Sea Lion (Zalophus japonicus), as extinct. Four additional species, the Galapagos Fur Seal (Arctocephalus galapagoensis), the Steller Sea Lion (Eumetopias jubatus), the Australian Sea Lion (Neophoca cinerea) and the Galapagos Sea Lion (Zalophus wollebaeki), are listed as endangered.
The basic description of their biological traits remains consistent over the centuries. The 1901 publication, Zoological series By Field Museum of Natural History, for example, describes them as follows:
Aquatic carnivora, with the limbs enclosed in the general tegument beyond the knees and elbows. Five digits on each limb, the first and fifth of the hind limbs generally the longest and stoutest, those of the front limbs decreasing in size from first to fifth.
Body and neck elongated; fore feet nearly as large as the hind feet; the latter capable of expansion, and with distinct claws on the three middle digits, front feet without claws; tail very short; when walking hind feet are turned forward under the body, supporting it; ears external; interorbital constriction of skull great; facial portion short, rather broad; two central pairs of upper incisors with a transverse groove; postorbital processes developed; alisphenoid canal present. Testes external in scrotum."True Seals
The family Phocidae, better known as the true seals or earless seals, consists of nineteen species, grouped into thirteen genera.
Elephant seals, the largest Phocidae (true seals or seals without ears) consist of two species, the northern elephant seal (Mirounga angustirostris) pictured above, and the southern elephant seal (Mirounga leonina).
While size may partially account for their name, the male's extended nose, which resembles an elephant's trunk, better explains the elephant name.
Harbor seals (Phoca vitulina) make their home along many coastlines in the northern hemisphere, where they tend to congregate in small groups.
Sometimes called sea dogs, their disposition appears that of a family pet, You often find them fishing close to shore or around harbors and other areas where fishermen bring home their catch of the day.
The basic description of their biological traits has not changed over the centuries. The 1901 publication, Zoological series By Field Museum of Natural History, for example, describes them as follows:
Neck short; hind limbs useless for terrestrial progression; palms and soles of feet hairy; no external ear; testes abdominal, no scrotum; skull without postorbital processes and no alisphenoid canal; auditory bullae inflated.
Five developed claws on each foot, those of hind feet subequal, the first and fifth not greatly exceeding the others in length; not extending beyond toes."
All Phocidae are considered top notch swimmers, however all of them also return to land or ice for breeding.
An examination of Phocidae range reveals a geographical divide, with most of the species split on the basis of their having either a Circumpolar North (areas in and around the Arctic Ocean) or Circumpolar South (areas in and around the Southern Ocean) territory.
The grey seal (Halichoerus grypus) and the harbor seal (Phoca vitulina) generally buck the trend, having a wide, Northern Hemispheric range, primarily limited to near shore temperate water environments.
While the populations of the northern and southern Phocidae groups are considered stable, the same can not be said for the more geographically distinct species.
The IUCN, for example, lists the Caribbean Monk Seal (Monachus tropicalis) as extinct, with three additional species, the Caspian Seal (Pusa caspica), the Hawaiian Monk Seal (Monachus schauinslandi) and the Mediterranean Monk Seal (Monachus monachus) as either endangered or critically endangered.
© 2013. Patricia A. Michaels