Earless seal

True seals live in the big ocean.

Most live in cold water. One kind lives in fresh water.

These seals swim with their bodies. They use back flippers to push. They use front flippers to steer.

On land, they cannot walk. They wiggle like worms to move. They make sounds like grunts. Some seals even sing under the water. They are very good at diving deep.

Earless seals are also called true seals.

They live in oceans all over the world. Most like cold water. One kind lives in fresh water.

These seals are great swimmers. They move their bodies side to side. They use front flippers to steer. They use back flippers to push them forward.

On land, they are clumsy. They cannot walk like sea lions. Instead, they wiggle their bodies to move. People call this galumphing.

True seals are built for deep diving. When they dive, air moves into special parts of their body. This helps them stay safe from pressure. They also have a layer of blubber. Blubber is a thick layer of fat under the skin. It keeps them warm in cold water.

Mother seals make thick milk for their pups. This milk has a lot of power. It helps pups grow fast. Many pups do not eat at all for a long time. They live off their own fat while they grow.

This helps them get ready to swim and hunt.

Earless seals are also called true seals or phocids.

They belong to a group of mammals called Pinnipedia. Most true seals live in cold polar or temperate oceans. However, the Baikal seal lives only in fresh water. These animals are very different from fur seals and sea lions. People sometimes call them crawling seals because of how they move. They are built to be excellent, long-distance swimmers in the deep ocean.

To swim, phocids move their bodies in a sideways motion.

They use their front flippers mostly for steering their direction. Their hind flippers provide the power for underwater propulsion. On land, these seals are quite clumsy and slow. Their hind flippers are attached to the pelvis and cannot rotate forward. Instead, they move by wriggling their bodies and using their bellies. This unique way of moving on land is called galumphing.

Scientists have studied how these seals changed over a long time.

The oldest known fossil is called Noriphoca gaudini from Italy. This fossil dates back to the late Oligocene or early Miocene. Other early fossils from the mid-Miocene lived in the north Atlantic. Researchers once thought they came from otter-like animals in Europe. Now, evidence suggests they may share an ancestor called Enaliarctos. This ancestor was likely related to bears and mustelids.

True seals come in many different sizes and shapes.

The ringed seal is quite small in length and weight. In contrast, the southern elephant seal is the largest member of the order Carnivora.

Seals use different ways to eat, such as suction or filter feeding. The leopard seal is a great example of this variety. It uses grip-and-tear feeding for penguins and filter feeding for krill. Some seals, like the Saimaa ringed seal, have very few members left.

Raising a pup is a very hard job for a mother seal. Most mothers must fast and not eat while they nurse. They produce thick, fat-rich milk to give pups lots of energy. This helps pups build up their own fat stores quickly. Once nursing ends, the pup must live off its own fat. This fast can last from two weeks to twelve weeks.

This period helps them grow the muscles needed for deep diving.

Earless seals, also known as phocids or true seals, are a major group of mammals within the lineage Pinnipedia.

These animals are members of the family Phocidae. They are often called crawling seals to distinguish them from the family Otariidae, which includes sea lions and fur seals. Most phocids live in the oceans of both the northern and southern hemispheres. They generally prefer polar, subpolar, or temperate climates. However, the monk seals can live in more tropical areas. One unique species, the Baikal seal, is the only seal that lives exclusively in freshwater.

Phocid biology is highly specialized for life in the deep ocean.

To swim, they use a sideways motion of their bodies. Their front flippers are used mainly for steering. Their hind flippers provide the primary underwater propulsion. Because their hind flippers are bound to the pelvis, they cannot rotate them forward to walk. This makes them clumsy on land. They move by wriggling with their abdominal muscles and front flippers. This motion is often called galumphing or lolloping.

These seals have many adaptations that help them dive to great depths.

When a seal dives, air is forced from the lungs into the upper respiratory passages. This prevents gases from being absorbed into the bloodstream, which protects the seal from the bends. The middle ear also contains blood sinuses that inflate during a dive to maintain constant pressure. To regulate body temperature, phocids can divert blood flow to a smooth layer of blubber under their skin. They also possess specific anatomical features like ear holes, retractable nipples, and internal testicles.

Phocid taxonomy is divided into two main subfamilies: Monachinae and Phocinae.

The Monachinae, or "southern" seals, include the tribe Monachini, which contains monk seals. They also include the tribe Miroungini, which consists of elephant seals. The tribe Lobodontini includes Antarctic genera like the leopard seal and the Weddell seal. The Phocinae, or "northern" seals, include the tribes Erignathini, Cystophorini, and Phocini. This latter group contains many common species like the harbor seal and the ringed seal. Recent molecular research has helped scientists confirm these relationships.

Scientists have used fossils to trace the history of these animals. The earliest known fossil is Noriphoca gaudini, found in Italy. This fossil dates to the late Oligocene or early Miocene. Other early fossils from the mid-Miocene appeared in the North Atlantic. Researchers once thought phocids evolved from otter-like animals in European lakes. However, new evidence suggests they share a single ancestor called Enaliarctos. This ancestor was likely related to bears and mustelids. It is now believed that many species, including elephant seals, evolved in the southern hemisphere before spreading.

Phocids show incredible variety in size and feeding methods.

The ringed seal is quite small, but the southern elephant seal is the largest member of the order Carnivora. To eat, they use at least four different strategies: suction, grip-and-tear, filter, and pierce feeding. The leopard seal is a notable example of an opportunistic feeder. It uses grip-and-tear feeding for penguins, suction feeding for small fish, and filter feeding for krill.

Their specialized skulls and teeth allow them to use these different methods.

Reproduction is a demanding process for phocid mothers.

Because feeding grounds are often far from breeding sites, mothers must fast while they nurse their pups. They produce thick, fat-rich milk to provide high energy in a short time. Nursing can last from only three days in hooded seals to seven weeks in monk seals. After nursing ends, the pup must live off its own fat stores. This postweaning fast can last between two and twelve weeks. This period allows the pup to develop the muscles and neural pathways needed for deep diving.