Seals are semi-aquatic mammals that are in a group called pinnipeds, which means fin-footed. There are 32 species of web-footed aquatic mammals that live chiefly in cold seas and whose body shape is round at the middle and tapered at the ends. It is adapted for swift and graceful swimming. The scientific name of a seal is Pinnipedia.
In this post, Pritish Kumar Halder takes a brief look at the Semi-aquatic mammal’s seal, its habits, types and related facts.
There are two types of seals: the earless (true) seals (family Phocidae); and the eared seals (family Otariidae). Which comprise the sea lions and fur seals. In addition to the presence of external ears, eared seals have longer flippers than earless seals. Also, the fur of eared seals is more apparent, especially in sea lions. Seals are carnivorous; they mainly eat fish and some also squid, molluscs, and crustaceans. The predators of the seals are killer whales, polar bears, leopard seals, large sharks, and human beings.
What Do Seals Eat?
All seals eat other animals, but most of them rely on fish caught at sea. Some of the few species depend on others like leopard seals make their living by hunting down penguins and other seals. Walruses are another species of seal, they survive on clams and other shellfish, which they detect with their highly sensitive whisker and then sucking up from the seafloor with their powerful mouths. There is also a species of pinniped known as crabeater. Crabeater doesn’t mean they actually eat crabs, they live in Antarctica. These seals use their highly specialized teeth to filter water for tiny, abundant crustaceans known as Antarctic Krills.
Types of Seals
Seals are a diverse group of semi-aquatic mammals in the Order Carnivora, the size of seals ranges from three feet three inches for the Balkan seal to 16 feet for the southern elephant seal which ranks as the largest carnivore. The streamlined body of seals features four limbs which have been modified to function as flippers when compared to dolphins, seals are more agile and flexible.
Most seal species live in the cold waters of the Southern and Northern Hemispheres. The animals mate and give birth on the shores and also escape to the beaches from predators such as killer whales and sharks. According to sea animals information seals are classified into two types: earless seals and eared seals.
Some of the earless seals are mentioned below:
They are classified in the Phocidae family. They grow from about 2.6 feet in length at birth to an average of 7.9 feet once it reaches adult form. The lifespan of this animal is 20 – 25 years and before they had a wide range of habitat, which included all Mediterranean offshore islands. Now its current habitat range has been reduced, it includes Cabo Blanco region in the northeast Atlantic ocean, the Aegean sea and the Madeira archipelago.
They mainly inhabits the northwestern Hawaiian islands including the Laysan and Lisianski Islands, Kure atoll, Perel and Hermes Reef, and the midway Islands. This animal prefers to live in warm subtropical waters, it moves to the land to breed, as well as haul out on the sand, volcanic rock and corals.
They live on the shore of the North Atlantic. The grey seals are large in size similar to Atlantic bulls can reach a length of 8.2 feet to 10.8 feet and females are 5.2 to 6.6 feet long. They prey on fish obtained at depths down of 230 feet or more and other prey are wrasses, sand eels, lobsters, gadids, herring, skates, and flatfish.
They are indigenous to the northernmost regions of the Atlantic Ocean and some areas of the Arctic Ocean. The shape of the seal is wishbone-shaped or black harp marks on its back and its body appears silver-grey in colour. When a pup is born, it is yellowish-white in colour but after some days it becomes white in colour. The length of the adult harp seal is five feet seven inches.
They are a uniquely restricted inland seal known as a landlocked Caspian seal. The uppermost body of the Caspian seal is greyish-yellow to dark grey with lighter grey sides and the back has irregular dark spots. They are listed as endangered species and it is especially vulnerable since Caspian seals live in a closed habitat.
They are the only recognised pinniped which is limited to freshwater habitats. The shape of the Baikal seal is torpedo and they have a flexible body, which makes them a graceful swimmer with the powerful hindquarters propel. Adult Baikal appears dark silver-grey on the upper side and yellowish-grey on the underside with dense sports fur. This seal only inhabits Russia’s Lake Baikal so-known as Baikal seal.
They live in the both arctic and the subarctic regions. It is one of the smallest seals found in the Arctic region, with a small head, a plump body, and a short cat-like snout. Ringed seal coat appears dark with silver rings on the sides and back, and a silver belly. The length of the Ringed seal is five feet on an average.
Their body is the pale underside, with rest having dark silver of grey. The coat of spotted seal has a pattern of dark spots, which are evenly distributed throughout the body. They have a round head with narrow and short flippers. Spotted seal habitat in the southern fringes of the pack ice in the beginning winter to early summer, after which it relocates to the coastal regions.
They inhabit the Northern Hemisphere of Arctic and temperate marine coastlines. Harbour seals are widespread among the seals with the presence in the coastal waters of the Pacific ocean, Baltic Ocean, Atlantic ocean, and the North sea. An adult Harbour seal can measure a length of 6.1 feet in length.
The name of the seal is inspired by the inflatable hood present on the forehead of an adult male. This seal habitat in the deepwater of the extreme north of the Atlantic ocean. They have silver or bluish-grey coats with scattered black blotches and spots. They are fairly antisocial animals, they gather only during breeding and moulting.
It habitats in the Arctic ocean and its shores and they are called Bearded seal due to its prominent and abundant whiskers. Those whiskers curl look quite elegant when they are dry giving the animal a “raffish look”. Bearded seals are the essential food source for the predatory polar bears and similar animals. Bearded seals feed on small prey present on the floor of the ocean like fish, squids, and clams.
And some of the other eared seals are Weddell seal, Leopard seal, Crabeater seal, Ross seal, Southern Elephant seal, Northern elephant seal, etc.
Now let us see some of the eared seals –
They are mostly distributed in subantarctic islands and its scientific name is to have come from the German vessel SMS gazelle.
Brown Fur Seal
They are also known as cape fur seal, it is the species of fur seal. It is the largest and most robust member of the fur seal.
Steller Sea Lion
They are also known as northern sea lions and it is a near-threatened sea lion in the northern pacific. It is one of the largest eared seals among pinnipeds.
California Sea Lion
It is a coastal eared seal native to western North America. They are sexually dimorphic in nature, males are larger than females and males have thicker necks compared to the female.
Australian Sea Lion
The scientific name of the Australian sea lion is Neophoca cinerea. Australian sea lions are known for their abnormal breeding cycles, which is varied from a five-month breeding cycle.
And some of the other earless seals are Guadalupe fur seal, Juan Fernandez fur seal, Galapagos fur seal, Arctocephalus Forsten, New Zealand sea lion, Subantarctic fur seal, South American sea lion, Galapagos sea lion, Japanese sea lion, and northern fur seal.
Characteristics of Seals
Some of the important characteristics of seals are mentioned below –
- They search for their food with the help of coarse and continuously growing whiskers. Seal sweeps its upper lip front and back to detect fish in musky water, using their sensitive whiskers.
- Seals have very good vision in water, actually, they must focus on both air and water, so they have very large and round eyes.
- They are very opportunistic feeders, they feed on preys depending on the availability.
- Seals have a very keen sense of smell in the air, which allows them to detect predators.
- Seals can hear in both water and air.
Where Do Seals Live?
Seals are found mostly along the coasts and the cold waters, but the majority of seals live in Arctic and Antarctic waters. Some of the seals like the harbour, ringed, ribbon, spotted, and bearded seals, as well as northern fur seals and steller sea lions, live in the arctic region.
Interesting Facts about Seal
- According to the seal information available, the seal can live on an average of 25 – 30 years, females usually live longer than the males.
- Seal weight ranges from 45 kg (Baikal seal and eared Galapagos fur seal) to 3,200 kg like a southern elephant seal.
- They have a layer of fat under the skin called blubber, which keeps them warm in cold water. Their slick fur coat is streamlined for gliding through water.