What Is The Difference Between Seals and Sea Lions?

Although both seals and sea lions come from the same taxonomical suborder of pinnipeds, which is a group of marine mammals that consist of sea lions, walruses, and seals, and have very similar outward appearances, true seals and sea lions are not the same. On closer inspection, they have some key anatomical differences in the ears, flippers, behavior, and family categorization. To understand the differences between these two marine mammals, we have to take a look back at their family taxonomy.

How The Pinniped Order Works

The pinniped suborder has thirty-three different species across three different family types – Otariidae, Odobenidae, and Phocidae. In the first family type, fur seals and sea lions are lumped together, in the second type are walruses, and in the third are true seals. It is common for people to refer to both the Phocidae and Otariidae as seals, however, it is important that there is a distinction between true seals, sea lions, and fur seals.

What Is The Difference Between Sea Lions and Fur Seals? 

The first, and one of the easiest ways to tell the difference between sea lions, fur seals, and true seals, is that sea lions and fur seals have external ears that protrude from their heads. True seals, on the other hand, actually do not have an external ear and instead have ear holes. In most cases, seals in the family Otariidae are known as eared seals, while those in the Phocidae are earless seals.

In addition to the ears being different, there is also a significant difference in the flipper length and the mobility between the two. Sea lions and fur seals have long flippers and are, therefore, able to rotate their back flippers. This rotation allows them to put their back flippers underneath their body and walk on land. True seals, unfortunately, cannot rotate their flippers underneath their body and so if they want to go on land, they have to flop around on their bellies. Another easy distinction to make is that true seals have very short front flippers.  This difference in flippers also changes how the two swim, with seals moving their back flippers from side to side like a fish’s tail, while sea lions and fur seals propel themselves forward as if their flippers are oars. Other than this, seals tend to have stubby front feet, thinly webbed flippers, and claws on each toe. Sea lions tend to have mostly skin-covered flippers and now claws at all.

Which Are Better Adapted For The Water?

When it comes to spending time in the water, seals tend to be better adapted to it. Although their bodies appear chubby, seals are more aqua-dynamic than sea lions as they tend to be smaller in size. Plus, due to the fact that their hind flippers angle backward, they tend to move faster through the water as the swimming movement doesn’t get hindered by their flippers.

Finally, sea lions and fur seals tend to be extremely noisy because they move around in groups while on land. True seals, tend to be less social as they spend more time in the water. The bellowing that you hear are often sea lions and fur seals communicating, but most true seals tend to grunt softly instead of barking.