Seals and sea lions: What’s the difference?

There are a few tricks to tell the difference between these two animal groups

ksweeney

September 13, 2017
Katie Sweeney

Biologist

 

Now that we have started seeing reports of northern fur seal sightings from citizen scientists in our remote camera images on Steller Watch, I thought this would be the perfect time to discuss the differences between seals and sea lions! Northern fur seals add a bit confusion as they have “seal” in their name but, are they true seals? The short answer is, “no!”

Pinnipeds can be found in waters all over the world, even some lakes!

Here’s the long answer…

Pinnipeds (or suborder pinnipedia, which means “feather-” or “flipper-footed”) include three different groups of animals: walrus (the Odobenidae family), seals (Phocidae family), and sea lions (Otariidae family). The walrus is the only species alive in the Odobenidae family and can be found throughout the arctic (North Pacific and North Atlantic Oceans). They are one of the largest pinnipeds and actually have air sacks in their chest that they can inflate to help them float, much like a life jacket (reference: Marine Mammal Center)!

classification
Generally accepted classification of the carnivora order. These sorts of classifications can change over time as new fossil and DNA evidence becomes available.

Seals, or ‘phocids’ (sounds like “faux-sids”), are often referred to as true seals or earless seals. They do in fact have ears though no external ear flaps, just small holes on either side of their head. Phocids also have small front flippers and while on land, galumph, or “inchworm”, to move around. At-sea, they use their hind flippers to propel themselves.

phocidae_peppermintnarwal
This is a great infographic showing different phocid species. Created by Peppermint Narwhal (via Facebook).

Sea lions, or ‘otariids’ (sounds like “oat-a-ry-ids”), are often referred to as eared seals include both sea lions and fur seals. Otariids have external ear flaps and large front flippers that they can rotate around and down in order to stand upright and “walk” on land. At-sea, they mostly use their large front flippers to propel themselves through the water. Fur seals do differ a bit from their fellow sea lion otarrids in that they have longer flippers and thicker fur. So, both northern fur seals and Steller sea lions are otariids and not phocids, or “seals”! Check out the images below of a northern fur seal pup and Steller sea lion pups showing those external ear flaps and upright posture and rotated flippers.

Pinnipeds can be found in waters all over the world, even some lakes! You may notice that there aren’t many species that inhabit warm tropical areas around the equator, though there are a few.

pinnipeds_natgeo1987_2
National Geographic infographic of pinniped species worldwide distribution (1987).

We will be sharing more about these northern fur seals in Alaska that many of you may start to see at Cape St. Stephens (Kiska Island) in remote camera images. There is an interesting project happening right now that I will share more about in our next blog post!


I have been a biologist in NOAA Fisheries Alaska Fisheries Science Center studying Steller sea lion population abundance and life history for over 10 years. I am an FAA certified remote pilot and have been flying marine mammal surveys with our hexacopter since 2014. I earned my B.S. in Aquatic and Fishery Sciences at the University of Washington and my Master in Coastal Environmental Management at Duke University. 

Author: Steller Watch

Blog for Steller Watch, a Zooniverse.org Project https://www.zooniverse.org/projects/sweenkl/steller-watch