What Are Seals?
Seals are marine mammals of the family Phocidae. They are distinguished from other mammals because they lack external ears. Instead, seals rely on touch, smell, and hearing to detect their prey.
In addition, they have a thick layer of fat under their skin to keep them warm in the cold water. Pinnipeds, which means “fin-footed,” are a class of semi-aquatic mammals that includes seals and the sea lion. Another member of this group is the walrus. Despite being related, all three belong to distinct taxonomic families.
How Many Types of Seals Are There?
There are two types of seals: earless seals and eared seals. Eared seals include sea lions and fur seals. The best-known earless seals are the true seals, including the elephant seal, walrus, and leopard seal. Earless seals lack external ears, while eared seals have them.
The Phocidae family includes “true” seals, commonly known as the earless seal, according to the Integrated Taxonomic Information System (ITIS). Along with numerous species of fur seals, sea lions are members of the Otariidae family, which also includes ear seals. In the family Odobenidae is walruses.
Seal Appearance and Behavior
Seals are generally black, gray, or brown. Some seals have patches of color on their fur. Seals range in size from the 1 m and 45 kg Baikal seal to the 5.6 m and 2,000 kg elephant seals. Most seals live in the ocean, but they can also be found in rivers and lakes.
Seals are good swimmers and can dive to depths of more than 1,000 m. Seals spend most of their time on land but must return to the water to mate and give birth. Female seals give birth to one or two pups. Pups are born with white fur, which they lose after a few weeks.
Seals are generally solitary animals but can be found in large groups on haulout beaches or in the water.
Did you know?
- Seals have flippers instead of legs and can move on land by crawling on their bellies.
- Seals can sleep underwater.
- The oldest recorded seal was more than 40 years old.
- Seals can stay underwater for more than an hour!
- Seals use vocalizations, including barks, growls, and whistles, to communicate.
- The Baikal seals are the smallest, and they only weigh 45 kg.
Seal Habitat and Diet
Seals live in the Arctic, Antarctic, and temperate waters worldwide. Some seals live in rivers and lakes. Seals eat fish, squid, and crustaceans. Some animals, like elephant seals, have evolved to hold their breath for up to two hours and dive to depths of more than 6,500 feet in search of food because they spend so much time in the water.
Although certain seal species will enter estuaries and rivers in quest of food, almost all seal species depend on saltwater areas. The Baikal seal, which lives its entire life in Lake Baikal, a freshwater lake in Siberia, is an exception.
In terms of evolution, bears, the family of mammals that includes weasels and otters, skunks, raccoons, and red pandas, are considered the closest relatives to seals. All seals consume other animals, most surviving on fish taken at sea.
However, a few species defy the norm. For instance, penguins and even other seals are the food source for leopard seals. Walruses also eat shellfish, which they find using their highly sensitive whiskers and then suck up with their powerful lips from the seafloor.
Antarctica is home to a type of pinniped known as the crabeater seal. However, contrary to popular belief, these animals don’t consume crabs. Instead, these seals filter water for the tiny, common Antarctic krill using extremely specialized teeth.
The Northern Hemisphere is home to the truest seals of the genus Phoca. There is not much size variation between the sexes, and they are generally small.
The harp seal has a large black blotch on its otherwise mostly silver-gray fur, the harbor seals have a marbled coat, and the ribbon seal has dark fur with ribbons of paler fur around the neck, front limbs, and posterior part of its body. The ringed seal has scars all over its body.
The global seal population is unknown, but it is estimated to be millions. The IUCN Red List lists 19 species of seals as being vulnerable or endangered. Some regional populations are at risk, including grey seals in the Baltic Sea. The hooded seal and northern fur seal are at risk.
In 2008, the monk seal of the Caribbean was deemed extinct. The world’s largest population of seals belongs to the crabeater species. According to the IUCN, there are 2 million to 75 million individual seals worldwide.
According to researchers, elephant seals have “smoker’s blood” because they have the same level of carbon monoxide in their blood as someone who smokes 40 or more cigarettes per day. The high concentration of gas in their blood, according to scientists, may serve to protect them when they descend to the depths of the ocean.
Harp seals have a 15-minute maximum underwater stay. And even more impressive are Weddell seals. the ability to remain submerged for up to 80 minutes. Only when they come across openings in the ice sheets above the ocean do they surface for air.
Threats to Seals
The biggest threat to seals is humans. Humans hunt seals for their fur, meat, and oil. Pollution and climate change are also threats to seals. Sea squirt species have historically been aggressively hunted for their fur, which has led to the extinction of some species.
The Caribbean monk seal, for example, vanished from the globe in the 1970s. Even though hunting is now more strictly regulated, animals are still at risk of starvation, entanglement in fishing lines, and conflict with fishermen. Some species, including the Hawaiian and Mediterranean monk seals, are in danger of extinction.
But climate warming poses the single biggest threat for many pinniped species, especially those that depend on sea ice. The United States Marine Mammal Protection Act of 1972 protects seals in U.S. waters. In Canada, the Marine Mammal Regulations protect seals.
Seals have predators, including killer whales, large sharks, and polar bears. Walruses exploit seasonal ice formations to graze for food further from the shore, whereas several species of Arctic seals depend on ice for reproduction.
Ringed seals carve holes in the ice and snow to form caves that serve as entrances to the ocean. The animals will be more vulnerable to polar bear predation if that snow melts earlier than usual.
Seal Reproduction, Babies, and Lifespan
Female seals give birth to one or two pups. Pups are born with white fur, which they lose after a few weeks. Seals have a lifespan of 20-30 years. Unlike other fishes, seal mothers and pups stay together on the coast and do not separate while nursing.
In the case of sea otters, moms will abandon their young ones on the shore so they can forage offshore. Male seals will make deep, throaty sounds during mating season to draw the attention of females.
Additionally, a male seal will call out to other males to let them know that his females have been claimed. When it comes to mating, males have fierce territoriality. They will strike and bite each other as they struggle for the right to mate. The winner has the opportunity to mate with as many as 50 local females.
Mothers carry their kids for about 10 months during the gestation period. Some seals may create sand nests in which to raise their young when they decide the time is right. Each year, sea lions and seals only have one pup. Others, such as the harp seal, give birth to their young immediately.
After weaning her pups, females will mate and become pregnant again. Because it takes them that long to get big and strong enough to win a mating struggle, males cannot mate until they are roughly 8 years old. A seal pup and her mom may communicate through sound.
The unique sounds of port seal pups can be heard up to one km. Using scent glands on their flippers and the skin surrounding their muzzles, moms and pups can identify each other when they are nearby.
Conclusively, it is suggested to keep your distance if you come across a port seal pup on the sand because its mother may be out at sea. Seal pups are drawn to moving things that are larger than themselves by nature. This can aid a pup in staying close to its mother and lead it to take unwise paths.
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