Pinnipeds, or seals and sea lions

Seals and Sea Lions

Seals, sea lions, and walruses all belong to the Marine Mammals. As mammals, they need to breathe air, give birth to live young, nourish their young with milk, have hair at some point in their life cycle, and are warm blooded, approximately the same internal temperatures that we experience. Once the mammal gets into the ocean, these functions become more challenging, and the marine mammals have adapted well and we will talk about their adaptations later.

The mammals contain several orders or groups of animals, one of which is the order Pinnipedia. The name refers to the fact that their feet (pedia) are in the form of fins (pin). This group is part of the larger group called Carnivora, and looking at the mouths of these animals will readily give you the idea that they are carnivores, feeding on animal matter, chief of which are fish, but not exclusively. The Pinnipeds are further broken down into 2 main groups, which are differentiated by:

Presence of external ear flaps in the sea lions and absence of those ear flaps in the true seals.

The ability of rotating their hind flippers under their body in the sea lions and the inability to do that in the true seals. This ability enables the sea lions to move well on land, and even stand up on their hind flippers or climb high onto rocks. The true seals move on land by ‘crawling’ and thus are always found very close to sea level while on land.

There are some other technical differences, but the two above will allow you to instantly separate out the sea lions (which includes the fur seal) from the true seals, of which the harbor seal is an excellent example.

In the next posting, we will discuss the 2 animals that are the most common in the waters off southern California, the California Sea Lion and the Harbor Seal.