There are three families of pinnipeds: the Phocidae, the earless or ‘true’ seals; the Otariidae, the eared seals, and the Odobenidae, the walrus. This article focuses on the difference between the earless seals (seals) and the eared seals (sea lions).
Phocidae (Earless or 'True' Seals)
- Have no external ear flaps.
- Swim with their hind flippers. Their hind flippers always face backward and are furred.
- Have 2 or 4 teats.
- Can be found in both marine and freshwater environments.
Examples of earless (true) seals: harbor (common) seal (Phoca vitulina), grey seal (Halichoerus grypus), hooded seal (Cystophora cristata), harp seal (Phoca groenlandica), elephant seal (Mirounga leonina), and monk seal (Monachus sp.).
Otariidae (Eared Seals, Including Fur Seals and Sea Lions)
- Have external ear flaps.
- Swim with their front flippers. Unlike earless seals, their hind flippers can turn forward, and they are better able to “walk” on their flippers.
- Have 4 teats.
- Are only found in marine environments.
Examples of eared seals: Steller’s sea lion (eumetopias jubatus), California sea lion (Zalophus californianus), and Northern fur seal (Callorhinus ursinus).Sources:
- NOAA Office of Protected Resources. 2008. ”Pinnipeds: Seals, Sea Lions and Walruses” (Online). NOAA. Retrieved November 23, 2008.
- Waller, Geoffrey, ed. 1996. SeaLife: A Complete Guide to the Marine Environment. Smithsonian Institution Press. Washington, D.C.