Fur Seals and Sea Lions (Otariidae)

Currently, Otariidae get classified into seven genera and sixteen different species:

• 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.

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 has not changed 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."

© 2010. Patricia A. Michaels