What kinds of seals are there in Antarctica?
Seals are distributed in almost all sea areas in the world, especially in cold sea areas. There are 34 species of seals in the world, about 35 million. There are 6 species of seals in the Antarctic region, about 32 million, accounting for 90% of the total number of seals in the world. Obviously, the Antarctic region is an important producing area of seals.
There are six species of seals inhabiting the south of the Antarctic convergence zone, namely sawtooth seals, elephant seals, leopard seals, Weddell seals, Ross sea leopards and sea lions. The largest is elephant seal, and the largest number is sawtooth seal. Among these six kinds of seals, sawtooth seal, leopard seal, Weddell seal and Ross sea leopard are unique to Antarctica. Antarctic seals are mainly distributed along the coast of the Antarctic continent, in ice floes and in the waters around some islands.
The fur, skin, meat and fat of seals have high economic value. Since the17th century, many explorers who went to the South Pole have hunted seals and used seal oil as fuel, making life very difficult. From 65438 to 1970s, some countries commercially exploited seals, which led to a rapid decline in the number of seals. In order to save seals from extinction, 1972, 12 Antarctic treaty countries concluded the Antarctic seal protection convention, which prohibited the killing of seals. In recent years, the number of seals has started to rise again.
Weddell's seal
Weddell seal is a clumsy animal, distributed on the coast of Antarctic waters. It is 3 meters long and weighs more than 300 kilograms. Females are slightly larger than males. Its back is black, other parts are light gray, and there are white spots on its side, the number is about 750 thousand. Every summer, molting begins. After molting, the body is dark gray or black, and the abdomen has beautiful white and silver gray stripes. Probably because of laziness, its body is as fat as a mollusk, lying lazily on the ice for a long time, forming a strange picture.
Weddell seal has a very special life habit. They often haunt the sea ice area and can spend a long and dark winter under the sea ice. It relies on sharp teeth, gnaws holes in the ice, sticks its head out to breathe, or drills holes in the ice to live alone, rarely in groups. When opening a hole, the seal saws the ice with its teeth and keeps the hole open with its big fangs. Therefore, the "ice saw" teeth of old seals, that is, the upper and lower fangs and a pair of front teeth, generally have obvious signs of wear or fracture. Many seals suffocate under the ice in winter because their fangs are damaged and they can't penetrate the breathing holes in the ice. Females live mostly on ice, males live mostly in water, and they mate in water. Weddell seals feed on fish, squid and krill.
In winter, the atmosphere is much colder than sea water. Weddell seals rarely come to the ice except on windless days, which shows that they have strong diving ability. Weddell seals often swim long distances under the ice. It is speculated that seals can use the gas accumulated under the ice to breathe, but the main factor for their survival is to keep the breathing hole open.
The pregnancy period of Weddell seal is 10 month. Every spring, females climb to the ice in droves to give birth. The lactation period is as long as 1 month, but the situation of seal calving in different parts of Antarctica is different. The peak of seal breeding in Ross Sea was in the late June of 10, while in Graham Land, it was 1 month earlier.
The newborn baby of Weddell seal weighs 27 kilograms and grows at an amazing speed. The baby's weight has increased by 1 times in 2 weeks, and there is a dense layer of fluff on his body. After 2 weeks, the whole body began to become hairy; By the sixth week, a hard layer of fur had grown. The calf can enter the water in 3 weeks, but it will continue to breastfeed for 7 weeks after birth, that is, before its mother leaves it.
Weddell seal cubs began to prey on crustaceans before the end of lactation, continued to prey on crustaceans for several months after weaning, and gradually turned to fish and cephalopods as food.
The young can grow to 2 meters in 1 year, reach the body length of an adult seal in the second year, and start breeding in the third year. Cubs rarely go ashore, and we rarely know their migration rules. However, we found a situation: some Weddell seals that accidentally migrated to the sub-Antarctic islands and the coasts of Australia and New Zealand were all cubs under one year old.
Crab-eating seal
Crab-eating seals, also known as sawtooth seals, are unique mammals on the Antarctic coast, just like Weddell seals.
In summer, when the coastal waters around most of Antarctica thaw, crab-eating seals climb to the shore in droves. Seals that eat crabs can be seen near the Ross coast and in the west of Graham Land. They come and go regularly. After winter, all kinds of seals leave the coastal waters as usual and will not come back until next summer.
Crab-eating seals are smaller than Weddell seals, but very flexible. Its body length is 2? It is about 5 meters and weighs more than 200 kilograms. The female is bigger than the male. Its body color varies from silver gray to dark gray, sometimes reddish, and its back is darker than its abdomen. Sawtooth seals have rows of sharp teeth in their mouths, which are staggered up and down, much like sawtooth, hence the name. It feeds on krill, and it is an illusion to call it a seal that eats crabs, because there are few crabs in Antarctica, which is not enough for it to eat.
Seals that eat crabs change their hair in autumn. The newborn hair is light yellow at first, and finally becomes pure white with irregular light gray spots, especially many ribs and lower back, which are colorful and beautiful. Crab-eating seals are also called "Antarctic white seals" when their fur is full of light spots.
Apart from their symmetrical posture, crab-eating seals are different from Weddell seals in one thing: when they are disturbed, they are very alert and react very quickly. When it attacks people or other animals, it first rushes forward with its mouth hoarse, then retreats to the nearest cave and disappears into the water. Because of its long face, its appearance is very eye-catching. When it panics or is angered by something, its arch mouth will rise and become wide and big, which is very similar to a domestic pig.
Among Antarctic seals, crab-eating seals are the most livable. Usually, they will gang up on the ice, and even in coastal waters, they will gather on the ice that does not float, only occasionally landing. Crab-eating seals move quickly and dexterously on ice and snow, and may have developed special crawling ability during evolution. When it crawls, it moves like a quadruped. Its soft and flexible body and forelimbs don't stick to one side of its body like a Weddell seal, but move alternately like a quadruped.
Crab-eating seals feed almost entirely on krill, which is extremely abundant in Antarctica. In the process of eating, its molars become filtering organs, and each tooth becomes several convex flaps bent backward, so when the upper and lower jaws are close together, a row of holes are left, through which water is filtered out of the mouth, and the rest krill is swallowed.
Female sawtooth seal is sexually mature for 2 years, pregnant for 9 months, and breeds on sea ice, giving birth to 1 each year, and each fetus has 1 offspring. In the warm season, sawtooth seals form a breeding family: a female seal leads several children, and sometimes a male seal will temporarily join in and live on the sea ice. In other seasons, they are active on the edge of ice floes.
Crab-eating seals often have obvious scars and scars. The nature and location of these scars indicate that this seal is likely to be frequently attacked by killer whales.
Crab-eating seals are the largest species of Antarctic seals, about 30 million, accounting for more than 90% of the total number of Antarctic seals; It is also the largest number of seals in the world, accounting for 85% of the total number of seals in the world. It is said that it is also the largest mammal in the world today.
Ross sea leopard
Ross sea leopard is about 2? 7 meters, the female is bigger than the male, with small head and big eyes, also known as the big-eyed seal. Their backs are brownish gray or black, their bellies are light, and their ribs are dotted with clear diagonal stripes. Its number is about 250,000 to 500,000, and it feeds on deep-water squid.
Like the crab-eating seal, the Ross sea leopard lives in an ice pack, but its food and lifestyle are different from those of the crab-eating seal. Crab-eating seals like to live in groups, while Ross sea leopard always likes to act alone. They don't live in groups They lie lazily on the ice and don't like activities, but they will run away quickly when chased by other animals.
Ross sea leopard has a very strange feature, that is, its neck is thick and has a neck fold, and its head can be retracted, almost completely hidden in the neck fold. Its front flippers and back flippers are very wide, which makes them swim much faster than other kinds of seals.
Carnivorous seal
Compared with other kinds of seals that are only distributed in the Antarctic, carnivorous seals are not only distributed in the ice groups along the Antarctic coast and sub-Antarctic, but also in temperate regions. This difference is mainly related to the food of seals.
Carnivorous seals not only prey on fish and cephalopods, but also often attack other seals and even seabirds. They mainly feed on penguins in Antarctic and dumb Antarctic. When it kills cormorants, petrels or penguins, it drags the catch out of the water, shakes it vigorously and wipes off the birds one by one.
Carnivorous seals eat a lot. When they are hungry, they even attack whales, so carnivorous seals are fierce and cruel marine animals. They are strong and have a large row of developed teeth in their mouths. In addition to the big teeth and front teeth, there is also a row of sharp molars. The young male carnivorous seal has a symmetrical, slender body and a large head, which remains this shape all his life. When the female animal changes, its predecessor becomes wider and wider.
Carnivorous seals develop slowly before sexual maturity, with females reaching sexual maturity in the third year and males in the fourth year.
Carnivorous seals are dark gray with shallow bottoms, and their necks, ridges and ribs are covered with special white and black spots. Before sexual maturity, seals' fur looks pale.
The breeding period of carnivorous seals lasts for more than 3 months, from September to 65438+February.
walrus
Elephant seal, also known as pictographic seal and walrus, is the largest kind of seal. Males are generally 4-6 meters long and weigh 2-3? 5 tons; Females are smaller than males and weigh half as much as males, so it is easy to distinguish between males and females. Its number is about 700 thousand.
Elephant seal has a unique and elastic muscle above its lips, which looks like an elephant's nose, hence its name elephant seal. The elephant seal's nose is usually soft and drooping. When it is angry or fighting, it will bulge very high and stretch very long, sometimes as long as 50 cm. The fur of elephant seals is grayish yellow and sometimes grayish white. With the change of age and season, the body color is slightly different. Elephant seals are ugly, clumsy, feed on krill and squid, like to live in groups and breed on land, and each child gives birth to 1 offspring.
Whenever the breeding season comes in August and September, groups of elephant seals will run ashore and start occupying territory and looking for mates. At this time, the beach became a paradise for elephant seals.
Elephant seals usually breed in hereditary territory. In order to occupy territory, male elephant seals often have a cruel struggle; The winner occupies a lot of land and has many wives and concubines. The loser is disappointed and finds another way out. On the beach, people can see a male elephant seal guarding dozens or even hundreds of female elephant seals day and night. These are his wives and concubines, and he is always on the alert for incoming enemies. Once rivals meet, they will fight to the death regardless. Both sides were furious, growling, opening their mouths and biting until the war became black and blue and bloody.
The male elephant seal is fierce and the female elephant seal is docile. Once the female walrus is possessed by an elephant on the high seas, she obediently follows her husband and lies beside him meekly. If the female elephant seal has irregular behavior and is found by her husband, she will be severely punished. There will also be fights between walrus couples, because the female walrus refuses to mate again after pregnancy. As soon as the breeding season is over, the male elephant seal goes out to sea to hunt and have fun, and the responsibility of raising offspring is entirely borne by the female elephant seal.
Leopard seal
The leopard seal is 3-4 meters long, the female is big and heavy, about 300-500 kilograms, but the male weighs only 200 kilograms.
Leopard seals are covered with spots and look like leopards. Fierce temperament, flexible movements, fast swimming, sharp teeth, sensitive sense of smell, good at attacking prey, often attacking penguins by surprise.
Leopard seals have a wide range of eating habits. They not only prey on krill, fish and cephalopods, but also eat penguins, birds and small serrated seals. Therefore, people call it a robber in the sea, which makes other kinds of seals afraid and avoid it.
The number of leopard seals is only 220 thousand. They mate in water and breed on ice, and each fetus gives birth to 1 offspring.