It’s easy to confuse two animals. Believe me, I do it much too often. I’m talking leopard vs. cheetah or emu vs. ostrich. But it doesn’t have to be as difficult to differentiate between two similar species as we make it out to be. As a matter of fact, seals and sea lions really aren’t that similar. Not if you’re clued up on the differences!
Overview
So, what exactly separates the two marine species? More importantly, why do we confuse them? As it turns out, seals and sea lions are same-same-but-different. And apparently fur seals fall into the same category as sea lions – not seals!
First of all, seals belong to the family Phocidae. This family includes:
- Phocinae (Northern Seals): bearded seal, hooded seal, ringed seal, Baikal seal, Caspian seal, spotted seal, harbor seal, gray seal, ribbon seal, harp seal.
- Monachinae (Southern Seals): Weddell seal, leopard seal, crabeater seal, ross seal, southern elephant seal, northern elephant seal, Mediterranean monk seal, Hawaiian monk seal, Caribbean monk seal.
Sea lions belong to the family Otariidae. This family includes:
- Arctocephalinae (fur seals): brown fur seal, Antarctic fur seal, Guadalupe fur seal, Juan Fernandez fur seal, Galapagos fur seal, New Zealand fur seal, Subantarctic fur seal, South American fur seal, northern fur seal.
- Otariinae (sea lions): Steller sea lion, Australian sea lion, South American sea lion, New Zealand sea lion, California sea lion, Japanese sea lion, Galapagos sea lion.
The most prevalent differences between the two pinniped subfamilies are their physical appearance, the sounds they make, and the size of their groups.
Habitat
Seals: You’ll find seals in the Northern Atlantic, North Pacific, and the Southern Ocean. They prefer polar, temperate, and tropical regions. Some seals prefer to live on sandy beaches, others prefer rocky ledges, while Baikal seals stay in freshwater locations. Honestly, they’ll live anywhere if there’s water.
Sea lions: They live in both the Northern and Southern Hemisphere, but you won’t find sea lions in the Northern Atlantic. They prefer any water from subarctic to tropical, and they also live on sandy beaches or rocky ledges.
Physical Appearance
Seals: Baikal seals are the smallest (up to 220 lbs.) and elephant seals are the biggest (up to 4,500 lbs.). Size wouldn’t be the best way to tell whether you’re dealing with a seal or sea lion.
Seals fan their furry and thinly webbed hind flippers to swim. It’s a real treat to see them propel their chubby bodies through water. But the poor things move a lot more awkwardly on land. We call their cringy movements galumphing.
They’ve got small ear holes on the sides of their heads that give them impeccable hearing. These holes aren’t visible to us, unless you get really close. Now you know why we refer to them as earless seals.
Sea lions: Steller sea lions are the largest (up to 2,500 lbs.) and Galapagos sea lions are the smallest (up to 175 lbs.).
Sea lions can walk comfortably on land because they use their long fore and hind flippers. They’re also slimmer, so it’s easier for them to move. They can reach up to 25 miles per hour in water.
Sea lions and fur seals are called eared seals. Yep, you can see their ear flaps. They’re small, but they’re there and they help them to hear very well on land and under the water.
Behavior
Seals: Seals are pretty intelligent. They can perform tricks, memorize information, and work through problems. They’re also much quieter and they don’t bark. They only growl, whistle, and moan. Then there’s the elephant seal. They stay true to their name by making nearly deafening trumpeting sounds. Just like real elephants.
Gray seals use their flippers to clap to attract mates and scare off rivals. But the rest of the seal species prefer to spend their time alone in the water. They’re very private and they only meet up once a year to mate.
Sea lions: Despite seals’ abilities to entertain, it’s sea lions that get ‘appointed’ to work in aquaria and marine shows because they move better on land.
They bark, growl, and groan very loudly to communicate with family and friends. They also differ from seals because they form groups. We call these groups herds or rafts, and they can consist of 1,500+ sea lions. The only Otariidae family members that spend their time alone are northern and Guadalupe fur seals.
Diet
Seals: Different seals have different diets. And they also differ according to the season. Harbor seals eat fish (herring, rockfish, salmon), crustaceans, squid, and mollusks. Leopard seals prefer penguins, seabirds, and smaller seals, while elephant seals eat lantern fish, rag fish, hake, and squid.
Sea lions: The same goes for sea lions because their diets also change according to the season and the species. The South American and New Zealand sea lions eat penguins. Steller sea lions enjoy cephalopods (squid and octopus), and the rest of the species feed off anchovies, rockfish, mackerel, sardines, herring, crustaceans, etc.
Conservation Status
Sadly, there are species of both seals and sea lions that are endangered according to the IUCN Red List. Some face bigger threats than others but the numbers of almost all species are decreasing. We are also certain that the Caribbean monk seal and the Japanese sea lion are extinct because researchers haven’t spotted one in 50 years.
Seals: One of the world’s loneliest animals, the Hawaiian monk seal, is critically endangered thanks to habitat loss. With a population of no more than 1,400 seals, they are becoming more and more lonely as the days go by. The same goes for the Caspian seal and the Mediterranean monk seal.
Sea lions: One of the animals of the Galapagos Islands, the Galapagos sea lion, is endangered. They face many threats, but the most prevalent is the effect that plastic pollution has on the population. Unfortunately, the Australian sea lion, New Zealand sea lion, and Steller sea lion are all facing the same risk of extinction.
Similarities
Here are some things that make seals and sea lions similar:
1. Unfortunately, both seals and sea lions form a part of the shark’s diet. I wouldn’t say this is a similarity to be proud of, but it’s the sad truth.
2. Furthermore, you now know that both seals and sea lions (and their cousin, the walrus) are pinnipeds. Pinniped is Latin for fin footed.
3. Lastly, in addition to their fantastic hearing, both seals and sea lions can see exceptionally well. Since they’re pinnipeds, they have the tapetum lucidum membrane behind their eyes. This membrane helps them with night vision and it increases the light that their eyes take in. That’s why their eyes glow from a certain angle.
