Seals and walruses

Seal and Walrus Facts

Classification:

• Kingdom: Animalia
• Subkingdom: Bilateria
• Phylum: Chordata
• Class: Mammalia
• Subclass: Theria
• Order: Carnivora
• Suborder: Caniformia
• Families: Otariidae (eared seals, including fur seals and sea lions, seven genera, fifteen species); Phocidae (true seals or earless seals, thirteen genera, eighteen species); Odobenidae (walruses)
• Geographical location: Seals, every continent; walruses, polar and circumpolar regions in the Northern Hemisphere
• Habitat: Mostly water, but they give birth on land or on ice floes
• Gestational period: Earless seals, ten to eleven months; eared seals, twelve months; walruses, fifteen to sixteen months
• Life span: For males, twelve to thirty years in the wild; females may have a life span of only eight to twelve years, although some live to twenty or even thirty
• Special anatomy: Strong hind flippers, strong arms; webbed digits, five toes and fingers

Seals and walruses belong to the same clade. They are pinnipeds, the term used to indicate a carnivorous and semiaquatic animal with webbed feet. Walruses are distinguished from seals by their tusks, which in mature males grow up to two feet long.

Walruses use their tusks to aid locomotion when they are on land, as a means of defense when they are physically threatened, and as shovels to plow the ocean floor to turn up the mollusks that constitute the major part of their diets. Walruses have strong, bristly hairs around their muzzles that are used to separate the meat of the mollusks from the shells.

Seal are gregarious creatures. In captivity, it is easy to train them. They bond quickly with humans. In their natural state, they tend to cluster together in groups, often with as many as a thousand of them lying in close proximity to each other on the seashore or on an ice floe.

Seal and Walrus Habitats

Seals are found on every continent, including Antarctica. Although most of them prefer the cold waters of the circumpolar regions, seals swim toward warmer waters to mate, then return to more frigid areas to give birth, often delivering their young on ice floes. Monk seals are found as close to the equator as the Galápagos Islands.

Most seals live in salt water, although Saimaa seals live in Finland’s freshwater lakes. Many of them were killed off by fishermen who claimed that they were eating all the fish in the lakes. The Finnish government intervened and made killing the seals illegal in 1955, but it was not until serious conservation efforts began in the 1980s that the population began to rebound. It is also illegal to use fishing nets in those parts of the lake where the Saimaa seals live and breed, because more than half of their offspring were getting tangled in nets and drowning.

Although they are warm-blooded animals that must have air to breathe, seals and walruses spend most of their lives in the sea. They are essentially aquatic. Their webbed feet and flippers provide them with easier locomotion in the sea than on land, where most of them move quite clumsily. Seals and walruses are strictly carnivorous animals whose diet consists almost exclusively of fish and mollusks. They may ingest some seaweed, but if they do so, it is by accident. These animals can close off their nasal passages so that water does not enter them when they submerged. They can remain under water for up to thirty minutes without having to return to the surface. Seals are more streamlined than walruses. Walruses usually are found in waters that are no deeper than sixty feet, although they can dive to three hundred feet. They explore the ocean bottom, using their tusks to dig into the sand for the mollusks they live on.

Physical Characteristics of Seals and Walruses

Most seals and walruses have substantial layers of blubber, constituting almost half of the body weight of most seals. When melted down, the blubber of a mature male elephant seal can yield ninety gallons of oil. Blubber serves as the chief insulating material in the cold waters where most seals and walruses swim. The blubber also provides buoyancy. Walruses can puff up blubber-rich areas in their necks to keep their heads above water when they are bobbing about in the ocean.

There are two families of seals, the true or earless seals, family Phocidae, and the eared seals, family Otariidae. The largest species of seal is the elephant seal. It is sometimes twenty feet long and can weigh as much as four tons. Even the smallest species of seal, the ringed seal, is quite large, weighing in at about two hundred pounds. At maturity it is about five feet long. In some species, notably the monk, Weddell, leopard, and crabeater seals, the male is smaller than the female. Among Phocidae seals, the male and female are of about equal size, but among the Otariidae, the male is larger than the female.

Seals communicate at various volumes. The northern elephant seal has such a loud call that it can be heard a mile way. The Ross seal has a chirping sound that can be mistaken for bird song. The Weddell seal has a soft, gentle call.

Walruses, of the family Odobenidae, are distinguished from seals by their two upper canine teeth that grow into ivory tusks harder than those of elephants. These sometimes reach lengths exceeding two feet. Walruses have small heads and no protruding ears. The eyes are small and deep-set. The body is small, but overdeveloped in the neck area. Bulls are up to twelve feet long and five feet wide. They often weigh a ton. The female is two-thirds the size of the male.

Mating and Reproduction

Most seals swim south to spawn, while walruses usually spawn in their northern water habitats. Male seals and walruses have multiple spouses, sometimes as many as forty at one time. The older, seasoned animals stake out the most attractive territory and attract females to it, creating substantial harems within their own venues. Older males often fight off younger males, who in the end must settle for inferior pieces of land and fewer spouses. Males mature at about five years of age and often continue to mate until past twenty.

Female walruses give birth to one baby eleven months after they mate. Female seals have similar gestation periods but sometimes deliver twins, although more typically they deliver single offspring. Walruses tend to mate again within a month of the delivery of a cub; seals in some cases mate every other year, although some deliver cubs annually.

Although some seals are solitary in winter, they gather at breeding time in rookeries on islands or ice floes, but also sometimes along stretches of beach. As few as a dozen seals may gather in a rookery, but sometimes there are as many as a million within a fifty-mile radius. The males arrive at the rookeries first to stake out their territory, the most favorable locations being directly on the water. In the northern hemisphere, females usually arrive in July.

Human Interactions with Seals and Walruses

Seals and walruses are benevolent creatures that seldom attack and that are accepting of humans. They are trusting enough to be vulnerable to those who engage in mass slaughters of the animals for their fur, their blubber, and, in the case of walruses, for their ivory tusks, from which scrimshaw is made.

Inuit and other people of the Arctic depend upon seals and walruses as part of their survival strategy in hostile environments. After they kill an animal, they treat it with reverence, sometimes making a replica of it from one of its bones or from a tooth or tusk. They wear such amulets around their necks to demonstrate their gratitude to the dead animal. When the Inuit people slaughter an animal, they waste no part of it. They eat the meat, render the blubber into oil with which they light their lamps and warm their dwellings, convert the hides into clothing and tentlike coverings, and use the tusks and bones to carve into scrimshaw.

When Europeans and Americans began to raid the seal and walrus populations, they did so indiscriminately and came close to annihilating these animals completely. Fortunately, governments stepped in to protect the endangered species and to end the brutal slaying of newborn cubs for their fur, although environmentalists have called for more stringent restrictions on seal hunting.

Those who quested after fur attacked seal cubs only days old, beating them bloody with clubs, stripping them of their fur, often while the cub was still conscious, and leaving their stripped bodies on the ice. People around the world were outraged by pictures they saw of such predation by humans upon defenseless seal cubs. They eventually called for this brutality to stop. Multinational agreements were drafted to protect these animals. The results have been encouraging as seal and walrus populations have finally begun to increase.

Principal Terms

amulet: an ornament worn as a charm against evil

carnivores: meat-eating animals

circumpolar regions: the regions around the North and South Poles

mollusks: a phylum of aquatic invertebrates, usually shelled, such as clams, mussels, and squid

muzzle: the area around the nose and mouth of an animal

pinnipeds: web-footed animals

scrimshaw: a type of art that involves etching or engraving images on pieces of ivory taken from the tusks of walruses or other animals

Bibliography

Bonner, W. Nigel. The Natural History of Seals. New York: Facts on File, 1990. Print.

Chester, Sharon. The Arctic Guide: Wildlife of the Far North. Princeton: Princeton UP, 2016. Print.

Fay, Francis H. Ecology and Biology of the Pacific Walrus, “Odobenus rosmarus divergens Illiger.” Washington, DC: US Department of the Interior, 1982. Print.

Gadamus, Lily, and Julie Raymond-Yakoubian. "A Bering Strait Indigenous Framework for Resource Management: Respectful Seal and Walrus Hunting." Arctic Anthropology 52.2 (2015): 87–101. Web. 10 Oct. 2016.

Laws, R. M., ed. Antarctic Seals: Research Methods and Techniques. New York: Cambridge UP, 1993. Print.

Lepthien, Emilie U. Walruses. New York: Children’s Press, 1996. Print.

US Fish and Wildlife Service. Walruses: “Odobenus rosemarus.” Washington, DC: US Department of the Interior, 1995. Print.