Many people confuse seals and sea lions, marine mammals often seen basking on coastal rocks or gracefully navigating ocean waters. While both are fin-footed creatures, known scientifically as pinnipeds, they represent distinct families with unique characteristics.
Not the Same
They belong to different families within the suborder Pinnipedia, which also includes walruses. Seals are classified under the family Phocidae, often referred to as “true seals” or “earless seals”. Sea lions, along with fur seals, are part of the family Otariidae, known as “eared seals”.
Key Distinguishing Features
One of the most immediate differentiators between seals and sea lions is the presence of external ear flaps. Sea lions possess small, visible external ear flaps on the sides of their heads, which is why they are called “eared seals”. In contrast, true seals lack these external ear flaps, having only small ear holes that are not outwardly visible.
Their hind flippers also show a significant difference in structure and function. Sea lions have hind flippers that can rotate forward and underneath their bodies, allowing them to “walk” on all fours on land. This adaptability enables them to move more agilely on land. Seals, however, have hind flippers that extend straight backward and cannot rotate forward.
The way they use their front flippers for propulsion in water also varies. Sea lions utilize their large, powerful front flippers for primary propulsion, moving them like oars through the water. This method allows them to be among the fastest swimming pinnipeds. Seals, conversely, use their smaller front flippers mainly for steering, relying on a side-to-side sweeping motion of their rear flippers to propel themselves through the water, similar to a fish’s tail.
Movement on land further distinguishes them. Because their hind flippers cannot rotate, seals move by wriggling or “galumphing” on their bellies in a caterpillar-like motion. Sea lions, with their rotatable hind flippers, can lift their bodies and walk or run on all four limbs, demonstrating greater terrestrial mobility.
Vocalization patterns also differ notably. Sea lions are generally very vocal and known for their loud barking, roaring, and bellowing, which they use to communicate within their large social groups. Seals are typically much quieter, communicating through softer grunts, growls, hisses, or moans.
Differences in their coat and overall appearance are also present. Sea lions typically have coarser hair and a more uniform coloration, often brown or golden brown. True seals generally have smoother, shorter fur, often with visible patterns such as spots or rings, and their skin can appear almost hairless when wet. The overall body shape of seals tends to be rounder and more torpedo-like, while sea lions often appear more streamlined with a noticeable neck.
Social behavior also sets them apart. Sea lions are highly social animals, frequently congregating in large groups called colonies, herds, or rafts on beaches and rocky shores. Many seal species, however, are more solitary, spending a greater proportion of their time in the water and coming ashore in smaller groups or alone, especially outside of breeding seasons.
Why the Confusion Exists
The common confusion between seals and sea lions arises from several shared characteristics and their overlapping habitats. Both are marine mammals that spend significant time in the ocean but also haul out onto land or ice to rest, breed, and molt. Their streamlined, torpedo-shaped bodies, adapted for aquatic life, contribute to their general resemblance, especially when viewed from a distance. This overarching classification often leads to a generalized perception that they are the same type of animal. Without close observation or specific knowledge of their distinguishing features, the average person might easily mistake one for the other due to their similar overall roles in marine ecosystems.