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

October 2005

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.

Visually differences are slight, but once you know what to look for it’s not too hard to tell seals from sea lions. The The biggest giveaway is on their head: Sea lions have external ear flaps that stick out on either side. Seals only have a pinhole opening. The lack of an ear flap 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.

The long , strong, flexible flippers can support sea lions’ weight on land, enabling them to walk on all fours in a partially upright position. A seal’s front flippers are short and not very strong. On land it has to move much like a caterpillar, inching itself along on its stomach.

Because of 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, and steer by pointing their heads, necks and 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  be able to escape.

Seals appear occasionally in North Carolina waters and frequently “haul out” to rest on beaches. Seeing a seal in the wild is exciting, however, they are wild animals, unpredictable and have a vicious bite. They are also protected under the Marine Mammal protection Act. Human interaction is not only ill-advised, but also illegal. People and pets should maintain a safe distance and never approach or try to return a seal to the water. If you spot what you think may be an injured or distressed seal on a North Carolin beach, please call the central coast marine Mammal Stranding network at 252-241-5119.