The term "pinniped' derives from the Latin word "pinna", meaning, wing or feather, and "pedis", meaning foot. Pinnipeds are amphibious, aquatic marine carnivores whose front and hind limbs are flippers. All pinnipeds had to modify the basic mammalian pattern, which is designed for life on land, into a body form adapted to life in the three dimensional environment of water. In order to thrive in an aquatic environment, pinnipeds had to evolve physiological and structural alterations to permit movement in a three-dimensional water environment, to prevent loss of heat in the cooler water, and to develop a suite of adaptations associated with maintaining activity while ventilating the lungs relatively infrequently - the whole comprising the physiology of diving. There were three generally recognized families in the Pinnipedia: Phocidae (true seals), Otariidae (eared seals), and Odobenidae (walruses).

Pinnipeds also spend considerable time on land along the arctic and subarctic shores of all the world's oceans (in contrast to the cetaceans and sirenians, which are completely aquatic). These shore activities include resting and sleeping, temperature regulation, as well as mating, giving birth, and nursing the young.

The Pinnipedia include three families: the Odobenidae, which today has only a single species, the walrus: the Otariidae, the eared seals, containing 14 species, and the Phocidae, the true seals, with 18 species. The similarities between the Odobenidae and the Otariidae are sufficient to justify combining them into a superfamily: the Otarioidea. It is possible that these two groups arose separately from the carnivore stock; the eared seals about 25 million years ago and true seals about 15 million years ago. The degree of relationship between pinnipeds and carnivores has been a matter of debate.

The Pinnepeds in our collections include the following specimens:

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Family Otariidae (Formerly Pinnepedia)

• Northern Fur Seal (Callorhinus ursinus)
• California Sealion (Zalophus californianus)
• Stellar Sea Lion (Eumetopias jubatus)

Family Phocidae

• Harbor Seal (Phoca vitulina)

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See "Walker's Mammals of the World" (fifth edition), by Ronald M. Nowak, Published in 1991 in Baltimore and London by the Johns Hopkins University Press.