Types of sea seals. seal species

Eared and real:

All about the seals of our planet

How to distinguish a gray seal from a ringed seal? After all, many still confuse them. It would not be a crime to call a seal a seal, but experts do not recommend calling a seal a seal. And yet, only a small part of the animals with flippers that inhabit the seas, lakes and oceans of our planet are represented in the Baltic region. We will tell you why the name “pinnipeds” does not exist, how eared seals differ from real ones, and how many seals live in Russia.

Pinnipeds are outdated! Of course, out of habit, we all call animals with flippers instead of legs pinnipeds - fur seals, gray seals, and even walruses. However, scientists have long excluded this detachment from modern classification. According to modern ideas, these animals have different ancestors.

Eared seals and walruses are closest to bears - from there they have a small head, and hard brown fur, and small auricles. It is believed that these animals descended into the water in the Pacific Ocean, although the earliest remains of the eared seal were found in France, in the Atlantic basin.

And the closest relatives of real seals are mustelids. From there, an elongated spindle-shaped body, and short limbs in relation to the body. For the first time real seals descended into the water in the northern part of the Atlantic Ocean.

Flippers in real and eared seals, as well as in walruses, developed in parallel - in an evolutionary way: after all, the paws of animals hunting in the water are not very comfortable. It is in the structure of the flippers that eared seals differ from real ones. The latter cannot stand on their hind flippers, and when moving on land, they simply drag behind them. But the sea lions - this is what the eared family is also called - calmly step over with flippers along the shore: their hind limbs are bent forward at the heel joint and look like a flattened leg!

Where do seals live? In the Northern Hemisphere, eared seals are found only in the Pacific Ocean. And in the South - they are found at the southern tip of the South American continent in the Atlantic Ocean, as well as off the southwestern coast of Australia in Indian Ocean. Walruses live only in the Arctic Ocean and adjacent basins of the Pacific and Atlantic Oceans- in general, around the North Pole.

Real seals also prefer colder waters - in polar or temperate latitudes. The only exception is the tropical monk seal. Subspecies of this animal inhabit the Black Sea and the Pacific Ocean near the Hawaiian Islands.

There are also three species of freshwater seals in the world, and two of them live in Russia. This is the Baikal seal and the Ladoga subspecies of the ringed seal. Third freshwater seal - Saimaa ringed seal, the only endemic mammal in Finland. According to experts, resettlement into fresh waters occurred by accident, and is associated with the retreat of glaciers. Previously, seals inhabited the seas, and when the glacier left, they found themselves isolated in inland waters. and adapted to fresh water. By the way, experts say that only the Baikal seal can be considered a truly freshwater seal. And the Saimaa and Ladoga seals are just freshwater subspecies of the harbor seal.

What are seals? The eared seal family includes 7 genera and, according to various classifications, 14 or 15 species. Only two species live in Russia - the sea lion, or northern sea lion, and the northern fur seal. Both species are listed in both the Russian and International Red Books. The sea lion is considered endangered, and the northern fur seal is a vulnerable species, according to the IUCN classification.

In the broad sense of the word, seals can be considered all representatives of the order Pinnipeds, 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 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 sea ​​elephant). However, even animals of the same species differ greatly in weight in different times 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, and the hands and feet got greatest development, and the shoulder and femoral girdle were 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 Earth. 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 are underwater 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 types prefer to hunt for different prey, for example, sea ​​leopard- on penguins, 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 the first time is constantly spent on ice. Babies grow fast thanks to extremely high-fat milk rich in protein.

• KEY FACTS
• Name: Gray (long-faced) seal (Halichoerus grypus); spotted seal (Phoca vitulina vitulina) and Baltic ringed seal (Phoca hispida botnica).
• Area: Baltic Sea
• Social group size: True social groups No; most species usually form breeding groups numbering hundreds or thousands of individuals
• Gestation period: 6-11 months (depending on the species), including the latency period
• Number of Cubs: One
• Self-reliance: 2-4 weeks

Pinnipeds live mainly in water, and most of them come to land only during the breeding and molting season. There are about 30 species of these animals in three families of pinnipeds. In this article, we will focus on public behavior pinnipeds from the Phocidae family, called earless or true seals. We will also consider the lifestyle of native species Baltic Sea, among which is the northern elephant seal (Mirounga angustirostris).

The social behavior of the elephant seal, whose males fight each other for control of a group of females called a harem, has been extensively studied by zoologists. During the year, elephant seals usually lead a solitary lifestyle and only periodically come out on land or ice in groups. Even the mother does not take proper care of her offspring. She rarely teaches them the skills needed to adult life, feeds newborn cubs with milk for only a few weeks and leaves them to their fate.

A crabeater seal rests on an ice sheet in Antarctica. Representatives of this species feed on plankton, capturing it with an open mouth while swimming and filtering it out. sea ​​water through the teeth.

Seals of the Baltic

In order to give life to future generations, seals must go to land or dense ice, because if a cub is born in the water, it will immediately drown. However, seals leave the water during molting. Having changed their habitat, they gather in groups, and during this period there is no trace of their hermit way of life. If the seals' skin is warm, they will grow new fur. On land, animals move very slowly, so they form massive clusters on land to protect themselves from predators.

All Baltic seals leave the water in spring or early summer and congregate in their traditional breeding grounds in the ice fields. In females that have been well fed during 8-9 months of pregnancy, cubs appear soon after entering the ice. Mothers need a solid supply of fat (i.e., subcutaneous fat), which provides them with vital energy for the time of feeding the cubs, because during this period females rarely manage to eat. Pups of female gray and spotted seals are born on open ice near the recesses that their mothers dig and clean in advance. Unlike them, female ringed seals dig caves over 2 m deep in the snow - so-called. haulouts, which may consist of several compartments.

Northern fur seals spend 6-8 months a year in the open sea and come out to rocky land only in summer, during the breeding season. The picture shows a colony of fur seals in Alaska (USA).

Offspring

Spotted seal pups are larger and generally better developed than other species. They are able to crawl and swim within a few hours after birth. Such early development favorable for a species that spends up to 75% of its life in water.

The gray seal takes less care of its pups than other relatives. The female feeds the babies with milk for only 14-17 days, and then they are left alone with all the dangers of life. Seal milk is very fatty, and during the feeding period, the cubs gain weight up to 2 kg per day. The reserve of subcutaneous fat formed in this way is very necessary for the puppy, because when the mother stops feeding him, he will not be able to eat until he gets to the water.

Usually, after two weeks, hungry puppies begin to master the water element. Babies get food on a whim, they are not helped by relatives, but often young animals follow adults to find good feeding places.

Female spotted seals and ringed seals pay more attention to their babies. The period of feeding the offspring lasts 4 and 6 weeks, respectively, at which time they themselves also sometimes manage to eat. Cubs of both species can swim from the very early age and sometimes accompany their mothers in search of food. This gives the kids the opportunity to learn the basics of a future independent life.

Rival males

Signs of the beginning of a conflict between two seals are menacingly open mouths of males, loud cries and a demonstration of sharp teeth. During a fight, males may bite each other on the neck and front flippers, or pin each other to the ice. During the mating season, male winners can achieve the location of more than ten girlfriends. However, this advantage must first be won. It happens that males successfully defend their territory, only reaching the age of 10.

Male spotted seals have a different strategy. At some point, they gather in areas popular with females and put on a "water acrobatics show" accompanied by underwater sounds. Females give preference to those males whose performance impressed them the most. Marriage rituals ringed seals are not well understood, but males are believed to defend underwater territories where mating takes place.

Coast of the Pacific Ocean in California (USA). The picture captures the moment of the struggle of two northern elephant seals in mating season. Before the fight, the animals open their mouths wide, bare their teeth and scream loudly.

Males of all species do not eat anything during the mating season and sometimes lose up to 25% of their weight. After the end of the mating season, adult seals - both males and females - leave the ice fields and regain their lost strength within a few weeks. During the rest, they prepare for the upcoming molt, when they will have to get out of the water and exist without food for some more time.

northern elephant seal

Like most pinnipeds, the northern elephant seal comes to land only during periods of molting and breeding. Males arrive at the "marriage territory" in early December and compete for the right to occupy it. The winner will receive the favor of all the females that enter his territory, which is why the males fight so fiercely for the best territory. In battles involving a clearly larger and more dominant male, the weak one usually concedes, and if the strength of the males is equal, the battle lasts until one of them wins. Approaching each other, the males rear up, reaching 2-3 m in height, inflate their trunks and roar loudly. If none of the rivals gives up, the seals make swift attacks: and injure each other with sharp teeth. Most of them have many scars from such battles. Sometimes battles of northern elephant seals: can lead to the death of one of them.

2-3 weeks after the arrival of males, females arrive at the breeding grounds, ready to give birth to babies. They choose sites with best conditions, forming harems. Females bring one cub 6-7 days after arrival and feed it with milk for about 28 days. During this period, the male - the owner of the territory - guards the harem. AT last days feeding males again mate with females.

The hard life of children

For babies, alien females are also a threat. If the puppy loses contact with the mother, he will join another female to feed on her milk. However, most often a foreign female does not allow this. Like other seals, during the mating season, she does not eat anything, and milk is formed due to the supply of subcutaneous fat. The female saves this valuable product only for her baby, because the chances of his survival in the future depend on the reserves of fat that he has time to accumulate during the feeding period. If a strange cub demands milk from a female too persistently, she can expel him or even kill him. The mother who has lost her cub only occasionally shares her milk with orphans, but the cubs she nursed rarely survive.

The dominant male usually takes care of a harem of 40 females. The larger the territory that the females occupy, the more difficult it is for the male to assert his right to them. Fierce competition between males leads to the fact that only a third of them have the opportunity to mate. Almost 90% of the cubs in a large colony are usually fathered by only a few successful males.

Although the lifespan of seals can be over 15 years, the dangers associated with protecting the territory and harem, as well as losing more than a third of the weight during the mating season, mean that males rarely have the strength to participate in breeding for more than 3-4 years. Most males die after two successful mating seasons.

Male swindlers

Other thieving males wait for an opportunity to challenge the dominant male when his strength is running out after actively fighting rivals. Still others, most often underdeveloped, more female-like males, may try to sneak into the harem in the hope that the dominant male will not notice them and try to mate with the females. However, it is undesirable for females to show their favor to such males, since their offspring may be weak. Most often, in such a situation, females scream, attracting the attention of the dominant male, who comes to the rescue and drives the uninvited guest away. Thus, females select only the strongest males as fathers of offspring.

Specialization went in a special direction in another group of tetrapods - in the order of pinnipeds, the most characteristic representatives of which are the so-called true seals, among a dozen species common in the seas washing the shores of the USSR, and in some of our inland waters (Fig. 385, 386).

In the water, seals stay almost constantly - there, they chase prey, and rest, and sleep, and go out on solid ground (most often on ice floes). for a long time only during breeding and molting. Thus, having become aquatic animals, they did not lose contact with the land, which was reflected in their external and internal structure.

Their body has a characteristic streamlined shape: it is valky, with a short and thick neck (meaning?) And with hind limbs extended backwards, in their outlines representing some kind of fish tail. The seals have short limbs, and their shoulder and femoral sections are hidden in the body, and the paws visible from the outside have been transformed into a kind of fins - into flippers.

The front flippers, like the paired fins of the fish, control turns, and when moving on the ground or on ice, they allow the seal to crawl, clinging to the uneven ground with its claws. The hind limbs always remain stretched back and do not take part in movement on land, and in water they serve as a powerful organ of movement.

There is a curious feature in the skeleton of the hind legs of seals, due to the peculiarity of the work they perform: they face each other with their soles and are wide flippers that forcefully push out the layer of water separating them, throwing it back like a steamship propeller. And we can see (Fig. 387) that the extreme fingers - I (big) and V (little finger) turn out to be the most developed, long and strong on them, that is, just those that are primarily reduced in terrestrial mammals (cf. . with the limbs of paired and odd-toed ungulates - Fig. 443 and 460).

The short tail is hardly noticeable and does not play any role in the movement of the seal.

From the smooth surface of the body of real seals natural selection He also removed the outer auricles, which hindered the speed of advancement, turning them into valves with which diving seals close the ear openings (the nostrils are also closed with special valves at this time).

The coat, which, with the constant stay of the seal in aquatic environment could no longer serve as a fur coat, consists of short and smooth bristles, tightly adjacent to the body without undercoat; such a robe, smooth to the point of glossiness, can be compared in its meaning to the same slippery scaly cover of fish.

On the head of the seal, in addition to the general coat, tactile vibrissae - whiskers are well developed.

The absence of a fur coat is made up for by the strong development of subcutaneous fat, which gives the seal's body its roundness. In addition to keeping warm, a thick fat layer reduces the volumetric weight of the seal; This is also facilitated by the recently discovered subcutaneous air sac, located on the right side of the animal and having communication with the trachea (therefore, it is possible that the air supply contained in the sac, in addition to its hydrostatic value, allows seals to stay under water even longer).

By general character adaptive traits Quadruped seals are somewhat reminiscent of penguins among birds.

Recent studies have found that seals can dive to depths of up to 320–350 m and remain submerged for up to 10 minutes. So they can dive under polar ice, then floating out in the openings formed between the ice floes. At the same time, it was noticed that seals make peculiar clicking sounds underwater; probably, it is they that allow the seals to determine the location of such breedings from under the ice with the help of echolocation.

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. Need 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.

Nerpa is the most common seal species in the Arctic, according to research National Administration oceanic and atmospheric phenomena(NOAA).

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

One of the most known species, according to NOAA, is considered the California sea lion. AT wild nature 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, sea ​​hare(beared seal), 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 between Asia and North America, and off the coast 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 The 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 reserve.