Pinniped

Pinnipeds, commonly known as seals, are a diverse group of carnivorous, fin-footed, semiaquatic marine mammals. They include the walrus, sea lions, fur seals, and true seals, with 34 living species and many more extinct ones known from fossils. These animals have streamlined bodies and limbs modified into flippers, allowing them to move flexibly and agilely in water. Though not as fast as dolphins, they are well adapted for swimming and diving, with some able to reach great depths.

Seals vary greatly in size, from the small Baikal seal to the massive southern elephant seal. They live mainly in cold waters of the Northern and Southern Hemispheres and spend most of their time in the ocean. They come ashore to mate, give birth, molt, or escape predators like sharks and orcas. Their diet consists mainly of fish and marine invertebrates, though some, like the leopard seal, eat large vertebrates such as penguins and other seals. Walruses specialize in feeding on bottom-dwelling mollusks.

Traditionally, indigenous peoples of the Arctic have used the meat, blubber, and skin of seals. Seals have also appeared in various cultures and are often kept in captivity, sometimes trained to perform tricks. Once heavily hunted for their products, seals are now protected by international law. However, some species, like the Mediterranean monk seal and the Hawaiian monk seal, are endangered due to threats such as accidental trapping, marine pollution, climate change, and conflicts with local people.

Etymology

The name "pinniped" comes from Latin words pinna meaning 'fin' and pes, pedis meaning 'foot'. The word "seal" comes from an old English word called seolh, which itself comes from an even older language called Proto-Germanic.

Taxonomy

Further information: List of pinnipeds

Pinnipeds, commonly known as seals, are a group of marine mammals that include walruses, sea lions, fur seals, and true seals. They belong to the order Carnivora and are part of the suborder Caniformia, which includes dog-like carnivorans. There are three main families of pinnipeds: Odobenidae (walruses), Otariidae (eared seals, including sea lions and fur seals), and Phocidae (true or earless seals). Today, there are 34 different species of pinnipeds living, with many more that have been found in fossils.

Scientists have studied pinnipeds for many years. They were first recognized as a special group by a German naturalist in 1811. More recently, studies using genes have shown that all pinnipeds likely came from one common ancestor, rather than from two different lines. These animals have special adaptations that help them swim and move on land, such as flippers and strong bodies. Some, like the walrus, have large tusks, while others, like the sea lions, can "walk" on land using their flippers.

Anatomy and physiology

Pinnipeds, known as seals, have streamlined bodies with flippers instead of legs. They have small ears and flexible necks. Their teeth are pointed to grip slippery fish. Walruses are special because they have long tusks.

Seals come in different sizes, from the small Baikal seal to the large southern elephant seal. Some males are much bigger than females, especially in species where males compete for mates. Most seals have fur, but walruses have sparse hair. Their fur helps keep them warm, and they also have thick blubber underneath their skin.

Seals swim using their flippers. Some move their front flippers like wings, while others use their back flippers to push through the water. On land, they move by flopping or walking on their flippers. Their eyes are good for seeing both underwater and in air, and they can sense vibrations in the water with their whiskers to find food.

Distribution and habitat

Living pinnipeds are found in cold oceanic waters, especially in the North Atlantic, the North Pacific, and the Southern Ocean. They do not live in the warm Indomalayan waters. Some seals, like monk seals and certain sea lions, can be found in tropical and subtropical areas, often where currents bring cooler, nutrient-rich water.

Pinnipeds live in many different water types, including coastal areas, the open ocean, deep waters near islands, brackish waters, and even freshwater lakes and rivers. The Baikal seal is the only one that lives only in freshwater. On land, seals use many surfaces such as rocky shores, sandy beaches, sandbanks, and sea caves. In polar regions, they often rest on fast ice and drift ice.

Behavior and life history

Pinnipeds have an amphibious lifestyle; they are mostly aquatic but come onto land to breed, molt, rest, or avoid predators. Several species migrate over vast distances, especially in response to environmental changes. For example, elephant seals spend most of the year at sea and travel long distances between their breeding and molting sites.

Pinnipeds dive while foraging or to avoid predators. The Weddell seal can dive up to 600 meters and stay underwater for over 70 minutes, while northern elephant seals can dive over 1,500 meters and stay submerged for more than an hour. Their diets mostly consist of fish and cephalopods, but they also eat crustaceans, bivalves, zooplankton, and warm-blooded prey like sea birds. Some species hunt alone, while others work together in groups. Pinnipeds are preyed upon by orcas, large sharks, and polar bears, among others. They often gather in groups to reduce the risk of predation.

Their mating systems vary, with some species being highly polygynous and others more monogamous. Males often establish territories or defend groups of females. After birth, mothers care for their pups, with some fasting while nursing and others foraging while the pups stay behind. Young pinnipeds usually start swimming on their own shortly after birth. Pinnipeds communicate through vocalizations and some can even understand simple commands and recognize each other by voice.

Human relations

In culture

Further information: List of fictional pinnipeds

Many cultures have included seals in their stories and beliefs for thousands of years. In ancient stories, sea gods and goddesses often had connections to seals. In some northern lands, people believed in magical seals that could change shape from seal to human. Today, many people think of seals as friendly, playful, and fun to watch.

In captivity

Seals and other seal-like animals are kept in special places around the world because people enjoy watching them. They have been kept since very old times, and they can learn to do tricks. Some places have big pools where the animals can swim, and others have smaller spaces. The most common animals in these places are California sea lions because they are easy to train. Some groups think it is not right to keep these animals in small spaces, as they need large ocean areas to live in the wild.

Hunting

Main article: Seal hunting

People have hunted seals for a very long time, originally using simple tools and later more advanced weapons. Seals are hunted for their meat, skin, and in some cases, their tusks. There are differences between hunting by local communities, who rely on seals for food and other needs, and large-scale commercial hunting. Some seal populations have grown after hunting was limited, while others remain threatened. Some countries still allow controlled hunting of seals, but this continues to be a topic of discussion around the world.

Conservation issues

Pinnipeds, or seals, face several threats to their survival. Many get caught accidentally in fishing nets and can swallow hooks, which can harm or kill them. Pollution from organic chemicals builds up in their bodies, especially because they are high in the food chain and have thick blubber. These pollutants can affect their health and ability to have babies.

Climate change also poses a big risk, especially for seals that live in polar areas. Less sea ice affects their breeding and survival. Some seal populations have grown so much that they sometimes conflict with people, such as using docks for resting or competing with fisheries. Laws like the Marine Mammal Protection Act of 1972 help protect seals, but managing these conflicts remains a challenge.