Tuesday, September 30, 2014

Seals vs. Sea Lions

I hear this one all the time. It's a perfectly understandable confusion; these two animals are very similar in a lot of ways. If you're not a marine scientist or even an aficionado, there's not a whole lot of reason or opportunity to learn what the differences are between a seal and a sea lion.

This post would be more accurately titled "True seals vs. Eared seals" (more on this later). The family of pinnipedia is divided into three main categories: walruses, the eared seals (sea lions and fur seals) and the true seals (like the harbor and elephant seals). Within the eared seals, there are several types of fur seal, which have a thicker undercoat than sea lions. But aside from typical nit-picky species differences, fur seals and sea lions look pretty much alike. Therefore, since it's the only good image I've taken recently, the photo I'm using to illustrate the eared seals is a northern fur seal.

There are lots of similarities between true seals and eared seals. They're both mammals. They both belong to the family of animals called pinnipeds (meaning "wing-foot"). They have five digits on each flipper. And they both have sensitive whiskers for the detecting, pursuing, and capturing of prey.

But once you actually see them side by side, the differences become a lot clearer. 

This is a an eared seal (and a human, if you want to be pedantic about it):

My photo, and you're about to see it a lot.

This is a true seal. A harbor seal, to be exact:

From Wikipedia
You'll notice several differences immediately, but the biggest one is their general body type. The eared seal is definitely more of an athlete, with a svelte, lean, muscular body. The harbor seal is, er, well, more of a fast food and binge-watching TV sort of animal. Rounder. More to love, and all that. 

Both animals are very differently equipped. The eared seal has a rotating pelvis-- it can pull its rear flippers under its body and "walk" on all fours. Please excuse my terrible MS Paint illustrations of this:


In Rotation


Here's that standing eared seal photo again, with the rear flippers highlighted:

With true seals, their locomotion is primarily reliant on the amount of blubber they contain. Basically, it goes like this:

A true seal's flippers are much smaller, partly to stay out of the way when they go bouncing along.

Both animals are graceful in the water (though eared seals can move a bit more quickly), but eared seals got the upper hand out of the water, too. 

You can also look at color. Eared seals are pretty much universally a dark brown. They may have some blondishness from sun bleaching, but for the most part, they're chocolate colored. True seals are usually seen in a wider range of colors (all neutrals, but more varied, for sure). The harbor seal is spotted, for example. 

But if you're on a boat and you look in the water and see both animals looking up at you, there's one fast and easy way you can tell them apart. 

Sea lions and fur seals have external ear flaps (little coverings for their ears), hence the family name "eared seal":

True seals don't:

My photo

So, that's the difference. Wasn't that fun?!

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