Did you know that pinnipeds are true sea-lovers? They’ve got two sets of eyelids, just like their whale and dolphin cousins. They’re found in the water, on land, and can even walk on it—it’s proof they wasted no time with the transformation from terrestrial life to ocean life. Despite all this versatility and ability to adapt, there are some things you can easily tell from a pinniped: Walruses have tusks while seals have nothing but tiny holes for ears!

Anatomy, Diversity, and Evolution

Pinnipeds have streamlined bodies that can cut through water quickly. They’ve developed flippers on the rear end to propel and steer themselves through the water. Unlike whales and dolphins, sea lions are extremely flexible and can almost bend in half.

Propulsion and Movement

Though able to move on land and sea, pinnipeds are the most efficient underwater. Some species spend the majority of their life in the ocean—female northern elephant seals spend 66 percent of their time in the open ocean. Seals and sea lions propel themselves through the water in different ways. For the sea lion, swimming is all about front flippers with a “clap” motion. Sea lions are also known for porpoising to improve their speed, while female northern elephant seals make incredible journeys across long distances.

Salt Water

Pinnipeds that live in the sea need freshwater to survive, so their bodies undergo unique adaptations for this purpose. Their kidneys are especially efficient at retaining water, which makes their urine saltier than the surrounding seawater.

Staying Warm

Water is one of the most efficient coolers as it can absorb heat 25 times faster than air. For some animals, like pinnipeds, this means that they need an efficient way to retain body heat. Pinnipeds are chubby animals with thick layers of blubber that helps them maintain their warm core temperature in the extreme cold—even the smallest seals are noticeably rotund shapes.

In addition to blubber reserves, marine mammals may also incorporate a fur layer to gain additional warmth from the outside environment. Generally, marine mammal species are larger than terrestrial ones. This adaptation helps minimize the area of skin in contact with water and helps these animals stay warm in cold waters or frigid temperatures where water is present 100 percent of the time.


Pinnipeds need very different vision assistance since they see slightly above and below sea surfaces. The eyeball (which is connected to the cornea) on land requires a refraction property (a bending of light) in order to focus images in both locations. Terrestrial animals become farsighted when the eye fluid does not bend enough and the image does not focus properly for them. Pinnipeds have round lenses that work perfectly for underwater vision, being able to see twice as much as humans can see underwater.


Sea lions have an altered gene which means they cannot detect sweet taste. They also don’t have umami receptors, which detect savory and bitter tastes.


Pinnipeds are a particularly vulnerable species because they rely on their vibrissae to hunt prey. Wide-ranging and hunted to near extinction, they use their vibrissae on their faces to detect food. These complex facial hairs are extremely sensitive and can even detect the subtle water movement left in the wake of fish by their undulating fins.


Pinniped ancestors made the transition from land to sea, and they needed to adapt both on land and in the water. This included auditory evolution, and when underwater sound vibrations cause the entire skull to vibrate, not just the membranes in our ears. This is why sound underwater sounds garbled to humans. With ear bones that are six times bigger than ours, pinnipeds have an advantage as well. They close their ears when underwater so they can pinpoint a source of sound much easier.


Pinnipeds are a group of diving birds that includes the families Odobenidae (walrus), Phocidae (true seals), and Otariidae (fur seals and sea lions). Today, there are 30 species. In many cases, the males may be significantly larger than the females. Most close relatives include bears, weasels, racoons, skunks, and red pandas.


There are 19 species of seal worldwide and each specialize in a different type of habitat. Large animals such as the Southern elephant seal can weigh up to 500kg. Other common seals in the Arctic include the Greenland and Weddell seals and ice-floes. Most seals lack ear flaps for propulsion, but instead use their hind flippers for locomotion when on land.


Flippers of fur seals offer a diverse platform for walking and even running, making them able to search for prey or escape from attackers. Fur seals can be up to four times larger than female fur seals, with the males often being bigger and more powerful than the females.

True Seals

Seals (and sea lions) are a type of carnivorous mammal in the Carnivora order. They’re distinguished from true seals by their size and four-legged walking method. Sea lions are known for being vocal, expressing themselves with loud barks or cries. They are also social creatures that sometimes congregate in groups of up to 1,500 individuals. Unlike fur seals, sea lions have no significant coat and instead rely on blubber to stay warm.

Fur Seals

The most famous pinniped in New England was a seal called Andre. In 1961, Harry Goodridge, the harbormaster of Rockport Harbor, Maine, adopted a harbor seal found in the Penobscot Bay and named him Andre.

Named after his adoptive father, for the rest of his life Andre spent the warm seasons in Penobscot Bay. As a pup, he watched television with the Good ridge family and eventually performed daily shows at Rockport Harbor for tourists, a tradition that continued until his death at 25 years old in 1986. Today, a statue of Andre stands on the shore of Rockport Harbor paying homage to this much-loved animal. In recent times more than one sea lion and not a seal has been used to portray Andre in “Finding Dory.” Sea lions and walruses also play many side roles in a variety of cartoons and children’s films “Finding Dory,” the “Madagascar” films,”Ice Age 4,” and others.

Sea Lions

The most famous pinniped in New England was a seal named Andre. In 1961, Harry Goodridge, the harbormaster of Rockport Harbor, Maine, adopted an abandoned harbor seal found in the Penobscot Bay, Maine.

Named Andre, the seal chose to stay with Goodridge and the rest of his life he spent the warm seasons in Penobscot Bay. As a pup, Andre lived in the Goodridge house and would even watch television with him and his family. Later, he and Goodridge would perform daily shows for tourists on the docks for many years until Andre’s death at 25 years old in 1986.

Today, a statue of Andre sits on the shore of Rockport Harbor. During his life he attracted significant news coverage from around the world and later Paramount filmed a movie inspired by his story that was released in 2002. To the dismay of some seals and not a sea lion was used to portray Andre in this film (the sealions starred as themselves). Sea lions played many side roles in cartoons such as “Finding Dory” or “Madagascar” films or “Ice Age 4”.

Famous Pinnipeds

There are a number of famous seals in New England, but the most famous was Andre, found in 1961 by harbors master Harry Smith Goodridge. A harbor seal found on the Penobscot Bay, Maine, Andre was brought to live with the master who renamed him Andre. Goodridge spent the warm seasons of his life with Andre on the boats.

As a pup he watched TV with Burricular and later, they would perform daily shows on their dock for tourists. Eventually this involved also performing with tourists themselves which lasted until Andre died at 25 years old in 1986. Today rocks against his statue on a stake at Rockport Harbor and he has appeared in films like “Finding Dory” and “Ice Age 4.”

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