What protects walruses and seals from the cold. Walrus and seal: comparison of appearance and strength. The origin of species: a controversial issue

In the broad sense of the word, seals can be considered all representatives of the Pinnipeds order, but usually this name means animals from the family of true seals. They are closely related to representatives of the eared seal family (fur seals and sea lions) and walruses. Distant relatives of seals are, on the one hand, terrestrial predators, and, on the other, cetaceans, who have completely switched to an aquatic lifestyle. The variety of seals is relatively small, there are about 20 species in total.

Harbor seal (Phoca vitulina).

The appearance of seals clearly indicates their aquatic lifestyle. At the same time, they have not completely lost their connection with the land like cetaceans. All types of seals are quite large animals weighing from 40 kg (for seals) to 2.5 tons (for elephant seals). However, even animals of the same species vary greatly in weight at different times of the year because they accumulate seasonal fat reserves. The body of the seals is elongated and valky at the same time, the contours of the body are streamlined, the neck is short and thick, the head is relatively small with a flattened skull. The limbs of the seals turned into flat flippers, with the hands and feet being most developed, and the shoulder and femoral girdle shortened.

Common seal on land.

Usually, when moving on land, seals rely on their forelimbs and stomach, while the hind legs drag along the ground. In the water, the front fins act as a rudder and are hardly used for rowing. This differs significantly from the mode of movement of eared seals, which actively use all limbs to move both on land and under water. True seals do not have auricles, and the ear canal is closed by a special muscle during diving. Despite this, seals have good hearing. But the eyes of these animals, on the contrary, are large, but short-sighted. This structure of the organs of vision is characteristic of aquatic mammals. Of all the sense organs, seals have the best developed sense of smell. These animals perfectly capture smells at a distance of 200-500 m! They also have tactile vibrissae (colloquially called whiskers) that help them navigate underwater obstacles. In addition, some species of seals are capable of echolocation, with which they determine the location of prey underwater. True, their echolocating abilities are much less developed than those of dolphins and whales.

The "smiling" face of the leopard seal (Hydrurga leptonyx).

Like most aquatic animals, seals do not have external genitalia, or rather, they are hidden in the folds of the body and are completely invisible from the outside. In addition, seals do not have sexual dimorphism - males and females look the same (the exception is the hooded seal and the elephant seal, the males of which have special "decorations" on the muzzle). The body of seals is covered with hard, short hair, which does not impede their movement in the water column. At the same time, the fur of seals is very thick and is highly valued in the fur trade. The body of seals is also protected from the cold by a thick layer of subcutaneous fat, which takes on the main thermoregulatory function. The color of the body in most species is dark - gray, brown, some species may have a speckled pattern or a contrasting color.

Sea leopard on the shore.

Seals are very widely distributed; in total, the ranges of different species cover the entire globe. Seals have reached the greatest diversity in the cold latitudes of the Arctic and Antarctic, but the monk seal, for example, lives in the Mediterranean. All species of seals are closely associated with water and live either on the coasts of the seas and oceans, or on vast expanses of pack (perennial) ice.

A crabeater seal (Lobodon carcinophagus) naps on a drifting iceberg shard.

Several species of seals (Baikal, Caspian seals) live in isolation in the inland lakes of the continents (Baikal Island and the Caspian Sea, respectively). True seals roam over short distances, they are not characterized by long migrations like fur seals, for example. Most often, seals form group concentrations - rookeries - on the shore or on an ice floe. Unlike other species of pinnipeds (fur seals, sea lions, walruses), true seals do not form dense and numerous herds. They also have a much weaker herd instinct: for example, seals feed and rest independently of each other and only monitor the behavior of their brethren in case of danger. Between themselves, these animals do not quarrel (with the exception of the mating season), there have been cases when, during the molt, seals scratched each other's backs in a friendly way, helping to get rid of old wool.

Seals bask on the coastal cliff.

Seals on the shore are clumsy and helpless: they usually lie close to the water, from time to time diving into the polynya for prey. In case of danger, they rush to dive, while moving with visible effort, but once in the water they swim quickly and easily. Seals are able to dive to great depths and stay under water for a long time. The record holder in this is the Weddell seal, which can stay under water for 16 minutes, while diving to a depth of 500 m!

Seals feed on a variety of aquatic animals - fish, mollusks, large crustaceans. Different species prefer to hunt different prey, for example, the leopard seal - on penguins, the crabeater seal - on crustaceans, etc.

The leopard seal caught the penguin.

All species of seals breed once a year. During the rut, skirmishes arise between males. Male hooded seals have an outgrowth on their nose, which inflates when the animal is excited. Puffing out their noses and roaring loudly, Ukrainians fight for the attention of females. Elephant seals have a fleshy nose and look like a short trunk; angry males during clashes not only roar and puff out their noses, but also bite each other, causing serious wounds. Pregnancy of females lasts almost a year. Seals always give birth to only one, but large and developed cub.

In many seals, the pups are covered with children's white fur, which is completely different from the coloration of adults, so they are called pups.

Although pups at first cannot accompany their mother in the water, they are well adapted to low temperatures and spend the first time constantly on ice. Babies grow fast thanks to extremely high-fat milk rich in protein.

The pinnipeds order is a small group of approximately 30 species. There are three families:

• real seals;
• eared seals;
• walruses.

Predatory animals live mainly in water. They stay on land during certain life periods.

General characteristics

As already mentioned, the representatives of this group are walruses and seals. Let us describe their general characteristics. Pinnipeds are rather large animals with a maximum body weight of 3.5 tons and a body length of up to 6 meters. The elongated rounded body tapers towards the head and tail. The neck is thick and inactive, with the exception of eared seals. Most of the limbs are hidden in the body bag. A thick leathery membrane connects the fingers of the limbs, forming flippers. All this is typical for these mammals (order pinnipeds). In different species of animals, the claws are unequally developed.

They use their limbs only for locomotion. With the help of the hind flippers, animals make oscillatory movements. In this case, the main muscle load falls on the back of the body. The front flippers balance the huge body and act as a rudder. The listed signs of pinnipeds indicate their adaptation to the aquatic environment.

The skin is thick with coarse hair. The subcutaneous fat layer reliably protects against hypothermia. The teeth of this class of animals are designed only for holding and grasping food. The brain box is large, the brain is large. There are no external shells, but they have good hearing. When immersed in the auditory opening narrows due to the muscles. Pinnipeds can make barely audible sounds. The organs of smell are developed satisfactorily. Vision is practically absent. Vibrissae, which are long hairs, serve as the main animals.

While foraging, pinnipeds are able to stay in the water for a long time. The dimensions of the lungs are larger than those of terrestrial predators, and provide a complete exhalation and inhalation of a new portion of air. Lung tissue is elastic, thickened pleura, developed muscles.

Pinnipeds feed on crustaceans, molluscs, seabirds, and fish. Food is obtained only in the depths of the waters.

Walruses and seals prefer to rest on ice floes. Pinnipeds lead a herd life. The largest accumulations of animals are formed during the onset of reproduction and molting. Some prefer others to migrate.

Natural enemies are:

• sea ​​leopards;
• White bears;
• large sharks;
• killer whales.

Pinnipeds come ashore or on ice to mate and reproduce. At three years, puberty occurs. Usually one cub is born once a year. The body of newborns is covered with thick fur, which differs in color and texture from the fur of adults. After a few weeks, the fur of the younger generation changes. Babies grow up quickly, eating rich mother's milk. After the end of feeding, the cub becomes independent. Pinnipeds live up to 40 years.

walruses

The walrus is one of the largest mammals of the pinniped class.

Representatives of this class can be found in the Chukchi Sea, near the Franz Josef Land archipelago, off the coast of the Novaya Zemlya islands, in the shallow seas of the Arctic Ocean.

Description

Walruses have powerful tusks, 2-4 kg each, which protrude 50 cm above the gum. In females, they are thinner and shorter. The main function of the tusks is to extract food by loosening the sandy or muddy bottom surface. Walruses in length can reach up to 4 m, and weigh 1.5 tons. Despite this body weight, these are mobile and agile animals. The entire body of mammals is covered with hard and sparse reddish hairs. Subcutaneous fat up to 10 cm thick reliably protects against hypothermia.

Walruses do not freeze in icy water and are not afraid of severe frosts. Due to the presence of a subcutaneous air sac, which is connected to the pharynx, they do not drown in water during sound sleep. On the upper lip there are thick, mobile and dense vibrissae (sense organs) located in several rows. By the smell they learn about the approach of danger. They have poor eyesight. External auricles are absent. Nostrils and ear openings close tightly when immersed in water. Fins help animals dive and swim. The rear flippers help push off the surface of the earth and ice.

Lifestyle

Rookeries are arranged on ice floes or on coastlines. In case of danger, they panic, rise from their homes and, crushing each other, go into the water, leaving behind the carcasses of dead animals.

reproduction

Walruses breed from the age of five years once every three or four years. The walrus has one cub. The female feeds him until fangs (tusks) grow. She is a very caring mother and will never leave her cub in danger.

Threats

Uncontrolled walrus fishing led to a significant decrease in the number. Since the fifties of the last century, a ban has been established on their hunting. An exception was made only for the local population (Yakuts, Chukchi), who, under licenses, are allowed to hunt walrus in order to satisfy their personal needs. Some walrus species are included in the Red Book as endangered mammals.

seal family

The elephant seal is the largest representative of pinnipeds among seals and lives in the subantarctic and subarctic seas.

It got its name due to the presence of a leathery bag, which is located in the nose of males. The seal spends most of its life in the water. Males weigh more than three tons and are 6.5 m long. The weight and size of females depend on the genus to which they belong.

Pinnipeds are a commercial species of prey. The skins are used in the manufacture of shoes and clothing. The meat is eaten. The skins of young individuals are used as fur raw materials. The fur of seals is in special demand.

Fur seals, sea lions and walruses are oceanic mammals in the group of pinnipeds (Seals). The connection with water in seals is not as close as in whales. Seals need a mandatory rest on land.

The seals are related but are in different taxonomic families.

• The so-called Earless (true) seals are members of the Canidae family - Phocidae.
• Sea lions and seals are members of the Otariidae family (Sea lions).
• Walruses belong to the Walrus family.

The main difference between earless and eared seals is their ears.

• Sea lions have external ear flaps. These folds of skin are designed to protect the ear from water when the seal swims or dives.
• The "true" seals have no external ears at all. Necessary get very close to them to see tiny holes on the sides of the seal's smooth head.

Another difference between seal groups is their hind flippers:

In real seals, the hind flippers do not bend and do not tuck forward, but only back. This does not allow them to "walk" on the ground. They move on land with undulating body movements.

Sea lions (fur seals and sea lions) can move on land using their hind legs (flippers).

Third difference:

Fourth difference:

• Sea lions are noisy animals.
• Real seals are much quieter - their vocalizations resemble soft grunts.

There are 18 species of true seals and 16 species of eared seals.

The largest representative of true seals is the southern elephant seal. Massive male, weighing up to 8500 pounds. (3 855.5 kg). Female elephant seals are much smaller, but still weigh more than a 2,000 lb (907.18 kg) car.

Males measure about 20 feet (6 meters) in length, females are about half as long.

The smallest representative of true (earless) seals is the seal. The seal has an average body length of 5 feet (1.5 m) and a weight of 110 to 150 pounds (50 to 70 kg). Unlike other seals, male and female seals are about the same size.

The ringed seal is the most common seal species in the Arctic, according to a study by the National Oceanic and Atmospheric Administration (NOAA).

Of the 16 species of eared seals, seven are sea lion species.

One of the most famous species, according to NOAA, is the California sea lion. In the wild, these animals live along the west coast of North America. They are often seen basking on beaches and marinas.

Males average around 700 pounds (315 kg) and can reach weights in excess of 1,000 pounds (455 kg). Females weigh 240 pounds (110 kg) on ​​average.

Natural environment of seals (seals)

True seals usually live in the cold waters of the Arctic Ocean and off the coast of Antarctica.

Harp (harp seal), ringed seal (akiba), Icelandic hooded seal, bearded seal (lahtak), spotted seal (larga), bearded walrus and lionfish - live in the Arctic.

The crabeater, Weddell, leopard seal and Ross seals live in Antarctica.

Fur seals and sea lions live in the North Pacific Ocean between Asia and North America, and off the coast of South America, Antarctica, South West Africa and southern Australia. They may spend about two years in the open ocean before returning to their breeding grounds.

Some seals make caves in the snow. Others never leave the ice and poke breathing holes in the ice.

What do seals eat?

Seals primarily hunt fish, but they also eat eels, squids, octopuses, and lobsters.

Sea leopards are able to eat penguins and small seals.

The gray seal is capable of eating up to 10 pounds (4.5 kg) of food a day. He sometimes skips meals for several days in a row, and lives off the energy of stored fat. And often completely stops eating - during the mating season does not eat for several weeks.

All pinnipeds - from true seals (earless) to eared seals (sea lions) and walruses (tusked odobenids) - are carnivores. They are related to dogs, coyotes, foxes, wolves, skunks, otters, and bears.

How do Bellies appear?

When mating season arrives, male seals will make deep guttural sounds to attract the attention of females. The male seal also calls other males to duel with the help of sounds.

Seals are very territorial animals when it comes to mating. They will fight for the right to mate, hit and bite each other. The winner gets the opportunity to mate with 50 females in their area.

Pregnancy of the female lasts about 10 months. When they feel that it is time to give birth, some of them dig nests in the sand, where they have cubs. Other seals lay their babies directly on the iceberg, on the snow.

Belki, so called puppies of seals.

Seals and sea lions only have one pup a year. Baby pups will be nursed on the ground by their mothers until they are covered with waterproof fur. It may take about 1 month.

The females will mate and become pregnant again as soon as her pup is weaned.

Males are not able to mate until they are 8 years old because they need to be big enough and strong enough to win a mating match.

Some other facts about seals

All pinnipeds - seals, sea lions and walruses - are protected under the Marine Mammal Protection Act.

Most seals are not considered endangered, according to the Red List of the International Union for Conservation of Nature (IUCN).

However, there are a few exceptions.

The Caribbean seal was declared extinct in 2008.

• The Galapagos seal and the monk seal are both critically endangered.
• Some local groups, such as the Gray Seals in the Baltic Sea, are also at risk.
• Northern fur seal and hooded seal are also vulnerable.

Northern seals, Baikal seals and Ursula seals are also vulnerable animals. They are trying to breed at the New England Aquarium in Boston.

The crabeater seal, among the seal species, has the largest population in the world. It is estimated that there are up to 75 million individuals.

The elephant seal has what is called "smoker's blood" - it has the same amount of carbon monoxide in its blood as a person who smokes 40 or more cigarettes a day. Scientists believe that this high level of gas in their blood protects them as they dive into the deep levels of the ocean.

Harp seals can stay underwater for up to 15 minutes.

The results of the Weddell seals are even more impressive. Their record for staying underwater is 80 minutes. They only come up for air when they find holes in the layers of ice above the ocean.

Farallones Bay, California National Marine Sanctuary is home to one-fifth of the world's seals. These marine mammals believe they have found a safe haven within the sanctuary.

Pinnipeds are an extremely interesting detachment of mammals. Closely associated with the aquatic environment, they are well adapted to it. Their limbs-flippers are flattened, fingers are connected by a dense leathery membrane. Thanks to flippers, animals move very quickly in the water, where they spend considerable time.

In total, there are about 30 species of pinnipeds in the world - these are seals, walruses, seals, seals, sea lions, sea lions, etc.

Pinnipeds are close in origin to terrestrial predators, from which they separated in the Tertiary period. This group of animals is relatively young.

All animals included in the detachment are rather large animals, their length is 1.2-6 m, they weigh from 40 kg to 3.5 tons. The body of these animals is elongated, spindle-shaped, the neck is not sharply delimited from the head and torso. As we have already said, as a result of adaptation to swimming, the limbs of pinnipeds have changed and, moreover, have greatly decreased: most of them are hidden in the body of the beast, and the shoulder, forearm, thigh and lower leg are sharply shortened. Claws in animals are developed differently: in eared seals and walruses they are very small, and sometimes completely absent, but in real seals they are very visible, especially on the forelimbs. Flippers are only organs of movement; animals are not able to hold food with them.

The skin of pinnipeds is very thick, covered with short coarse hair, usually without down. This is one of the adaptations for a long stay in the water. The animals are protected from the cold by a thick subcutaneous layer of fat, which is especially dense in species that inhabit the subpolar latitudes and breed on ice floes.

The skeleton of a pinniped differs in that it lacks tubular bones and clavicles. The fact is that the extreme monotony of the movements performed by animals led to the fact that the clavicles were simply not needed. Yes, and the teeth of the representatives of the detachment are relatively simple, because their main task is to grab and hold prey, and not chew it.

These animals feed on fish, mollusks, crustaceans; sea ​​leopard - penguins and seals.

These animals have excellent hearing, both on the surface of the water and in the depths of the ocean. But they do not have auricles (only eared seals have preserved their rudimentary remains). When immersed in water, the external auditory opening is reflexively closed by special circular muscles. When swimming underwater, some pinnipeds make faint sounds ("click").

The sense of smell, like hearing, is well developed in pinnipeds. Moving downwind (with absolute silence), it is impossible to approach the rookery closer than 150-200 m, while against the wind, an observer or hunter, observing disguise, can get close to animals at a distance of 10-20 m, or even closer.

Vision in pinnipeds due to the flat cornea and the low ability of the lens to accommodate is weak. However, often aquatic vertebrates are generally short-sighted.

While foraging, seals and walruses spend a long time under water: walruses up to 16 minutes, real seals a little less - up to 15 minutes. The dimensions of the lungs in animals of this order are somewhat larger than in terrestrial predators. The circulatory system also helps seals stay underwater for long periods of time. They have more blood than land animals, and therefore their body is better supplied with oxygen. The mass of blood in pinnipeds is 10-15% of body weight, in a dog - 6-8, and in a pig - only 3-5.

And yet, pinnipeds, unlike cetaceans, have not completely broken with the land. These animals breed only on the shore. Some of them (seals, sea lions, monk seals, etc.) bring their cubs on the beaches of islands or mainlands, others (harp seals, walruses, hooded seals) give birth to offspring on floating ice floes or use shallow water ice near the coast for this.

Pinnipeds bring no more than 1 cub per year, and become sexually mature no earlier than 3 years. Small seals differ from adults: they are covered with thick embryonic fur, which they retain for several weeks. They don't have subcutaneous fat yet. Offspring grow quickly due to the fact that mother's milk is very nutritious.

Pinnipeds are valuable game animals. No wonder they have been hunted since time immemorial. Especially valuable is the skin and fat of animals, which are used in many sectors of the economy. But sometimes fishing was carried out too intensively and some species were endangered, such as fur seals. These animals were taken under protection, reserves and sanctuaries were created. Now the herd of animals has gradually recovered. Limited hunting is allowed for some species of pinnipeds.