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What’s the difference between a seal and a sea lion?

October 15, 2005


Visually, the differences are slight, but once you know what to look for it’s not too hard to tell. The easiest way to tell them apart is to look at their heads. Sea lions have external ear flaps that stick out on either side. Seals lack this external ear, having instead only a pinhole opening. The lack of an earflap makes seals more streamlined in the water.


Seals, sea lions, and walruses are the three marine mammals that make up the sub-order Pinnipedia, which means “fin footed.” Seals are designed for life at sea, while sea lions have adaptations that are useful on land.


Sea lions have long, strong, flexible flippers that can support their weight on land. This enables them to walk around on all fours in a partially upright position. Conversely, a seal’s front flippers are short and not very strong. When a seal is on land, it has to move much like a caterpillar, inching itself along on its stomach.

Monk Seal


The easiest way to tell the difference between seals and sea lions is to look at their heads. Seals have pinhole openings, like this monk seal. Sea lions have ear flaps.


Because of their weak front flippers, seals use their hind flippers to propel them through the water in a side-to-side, fish-like motion. The front flippers do the steering. Sea lions, on the other hand, propel themselves by flapping their powerful front flippers like wings. For steering, they use their heads and necks by simply pointing their bodies in the direction they want to go.


Seals are at a slight disadvantage for depending on their hind flippers for propulsion. Their natural predators, Orcas and sharks, approach from behind. An injury to a seal’s hind flippers greatly decreases its chances of surviving an attack. A sea lion, however, might still be able to get away, as is evidenced by fresh wounds and old scars on survivors.


Seals appear occasionally in our waters and frequently “haul out” to rest on our beaches. Please do not attempt to help them back into the water. If a seal is obviously sick or injured, call the National Marine Fisheries Service Marine Mammal Stranding Network at (252) 728-8762, but do not approach them. Seals do not understand people are trying to help and will defend themselves. If you see injured or dead marine mammals or turtles, remember it is illegal and dangerous to get too close.