The seal is a carnivorous mammal of the genus seal of the subfamily seal of the sea lion family seal.[17]It looks like a cute puppy, hence its name,[18]Because of its thick and smooth fur, it was given the title of "fur sea lion".The size of a seal is about the same as that of a seal, and its length is nearly 2 meters. However, its weight is much smaller, only more than 20 kilograms. Its limbs have also degenerated into flippers, so it moves slowly on land.The seal has a spindle shaped body, a round head, large eyes, small ears, and a long beard on its mouth;The skin on the back is brownish gray or dark brown, while the skin on the abdomen is pale, grayish white.Its forelimbs have five toes, with webs between the toes, and its hind legs are wide and fan-shaped, which is convenient for paddling.[19]The male seal can live for more than 20 years, and the female seal is shorter.[20]
Seals are widely distributed and inhabit all over the world, especially the Pribilov Islands near Alaska in the United States, which is also called the seal islands.[18]Carnivores not only feed on cod and frog fish, but also eat sea crabs and shellfish.[21]Social animals like to bask in the sun. In the daytime, they often gather in large groups on rocks, ice and snow to enjoy sunbathing, or they hunt near the sea. At night, they go ashore for rest.[18]At the end of spring and the beginning of summer, a large group of male sea dogs are the first to return to their birthplace, seize the territory and wait for the female sea dogs to reach the shore, mate with them and breed.[21]
In Chinese ancient books and records of traditional Chinese medicine, sea dogs are also known as "fat animals", because the testicles and penis of male sea dogs, commonly known as "fat umbilicus", can be mixed with other drugs to make traditional Chinese medicine.[22]A research group composed of researchers from the Natural Environment Research Council of the UK and the University of Bielefeld in Germany has found that climate change has effectively affected the survival of Antarctic sea dogs, with consequences including the overall number of sea dogs declining, newborn sea dogs losing weight, delayed birth period and even genetic changes.[23]
Figure of sealSeals, body length 150-210 cm, weight 45-270 kg[16]。The body is spindle shaped.The head is round, the snout is short, the eyes are large, and there are small earshells. The body is covered with bristles and short and dense fluff. The back is brownish gray or dark brown, the abdomen is light or the whole body is white, and the limbs are fin shaped. The hind limbs face backward in the water, and can bend forward after landing, and walk slowly with the limbs.The head is slightly round, the cheekbones are high, the eyes are big, the earshells are very small, the muzzle is short, and there are long whiskers beside.All limbs have 5 toes, with web between toes, formingPteropodThe tail is very short.[1-2]
The seal looks like a sea lion, but its body surface is hairy. It is also called "fur sea lion".The overall fur color of the seal is white, greyish or black brown. The mature male seal has dark brown fur, and there are some gray hairs on the shoulder.Female seals are light and grayish brown.Round head, 1 pair of eyes, large and round, without ear shell, long mouth, hard cheeks, nostril and both ears have valves, which can be opened and closed freely.Both front and rear limbs have 5 toes, with claws at the toe end and web between the toes, forming flippers;The forelimbs are small, the hind limbs are large, and the hind flippers are fan-shaped.The body color varies with age. The back of the adult is grayish yellow or grayish, with many brownish black or grayish black spots;The belly is milky yellow, and the lower collar is white with few spots.[1-2]
Habitat environment
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Sea dogs have migratory habits. In winter and spring, the sea dogs on the islands of the North Pacific Ocean leave the island and travel southward, spreading all over the North Pacific Ocean. Some of them travel as far as the coast of California, the United States, and some as far as the central waters of Japan.In the summer, the sea dogs scattered from all sides migrate toNorth Pacific Breeding in hometown.This migration process takes 8 months. On the way, they always keep at least 10 miles away from the coast and never go ashore. Nobody knows why.
Like to bask in the sun, mostlyReefThey like to live in groups on ice and snow.During the non migration period, sea dogs generally live in Alaska andSiberiaBetween the Pribilov Islands andComandore Islands。[3]
Life habits
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Seals are born with the ability to walk and swim on land.They are very good at swimming. Soon after birth, they can swim for 5 minutes at a speed of 15 miles per hour and can dive to 240 feet underwater.Seals are clumsy on land, but not as clumsy as real seals.The reason for this is that the former has larger flippers, which can speed up to 5 miles per hour.
Seals are social animals, and they also flock when migrating.the pacific oceanBeihaigouIt takes 8 months every year toBering SeaAndCaliforniaMigrate from coast to coast in the middle and never go ashore.The remaining four months are used for mating, reproduction and breeding.
Predation: cruise and hunt near the sea in the daytime, and go ashore to rest at night.Good sense of hearing and smell.Except in the breeding period, there is no fixed habitat, and it takes 1000 kilometers to hunt once.They usually hunt in the evening, which makes them avoid their natural enemies (sharks, whales, polar bears, etc.) to some extent.The latter seldom appeared in this period of time;At this time, the light is dim, and the seal is not easy to be found.
Sea dogs are carnivores, and their food sources are very wide, mainly including cephalopod molluscs, oriental cod, Alaska cod, trout, octopus eel, wolf fish, various sea squirts, etc.When catching fish, the seal will dive into the water, quietly follow the prey, and then bite the prey.The seals cannot chew, so they either swallow the food directly or tear it into small pieces and swallow it.What is particularly interesting is that stones, weighing up to 200-400g, are often found in seals' stomachs.It is difficult to determine the biological significance of these stones.Some people think that the purpose of their eating stones is to adjust their body balance, and stones can play a role in reducing their fat floatability.However, many biologists believe that these stones are used to grind food and help digestion just like the sand grains in a bird's burrow are used to grind grains.Others believe that stones are used to knock out parasites in the stomach. When parasites are killed by grinding, they will be vomited by the stomach.However, quite a lot of stones are also found in the stomach of young sea dogs who still feed on breast milk, which makes the above theory difficult to justify.So far, people have not found a convincing answer.[4]
Distribution range
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The North Sea Dog is distributed in the North Pacific Ocean and often inhabitsKuril IslandsThis area is located in the northern hemisphere waters north of 35 ° N, and occasionally in the Yellow Sea and East China Sea of China.The seal is divided into two genera, the north and the south,Callorhinus onlyBeihaigouOne, distributed inNorth Pacific Along the coast, its fur is of good quality, which is called sea dragon fur in China. Therefore, sea dogs are caught in large quantities and are in danger.The South China Sea has many species and wide distribution of the genus Canis, which reaches the north to the equatorGalapagos IslandsThe southernmost reaches the Antarctic and sub Antarctic, and can be seen in South America, Africa and the southern coast of Oceania.Sea dogs like to live in groups. Most sea dogs in the world live near Alaska in the United StatesPribilov IslandsTherefore, this archipelago is also called "Seal Island".In addition, when approachingKamchatka PeninsulaOfComandore Islands。Dry islandSome sea dogs live in groups on the islands near the islands and Sakhalin Island.[5-6]
It is distributed in Bouvet Island, the southern territory of France (Crozet Island, Kergueran), Heard Island and McDonald Islands, South Georgia Island and South Sandwich Islands.
Wandering: Antarctica, Argentina, Australia (Macquarie Native), Brazil, Chile (Juan Fernandez Native), St. Helena, Ascension Island and Tristan da Cunha Islands (Tristan da Cunha Islands), South Africa (Marion, Prince Island).[9]
South Australian seal (scientific name:Arctocephalus pusillus）：
Also called African and Australian seal, Cape seal, Brown seal, South African seal.
It is distributed in Angola, Australia (New South Wales, South Australia, Tasmania, Victoria), Namibia, South Africa (Eastern Cape, Marion, Prince Island, Western Cape) and Gabon.[11]
Subantarctic seal (scientific name:Arctocephalus tropicalis）：
Also known as the Amsterdam Island seal.
It is distributed in Argentina, the southern territory of France (Amsterdam Sao Paulo, Crozet, Kergueran Wandering), Heard Island and McDonald's Islands, Madagascar, St. Helena, Ascension Island and Tristan da Cunha Islands (Tristan da Cunha Islands), South Africa (Marion, Prince Island).
Drifting: Angola, Antarctica, Australia (Macquarie Native), Bouvet Island, Brazil, Chile (Juan Fernandez), Comoros, Mauritius, Namibia, New Zealand.[13]
It is distributed in Canada, Japan, the Democratic People's Republic of Korea, South Korea, Mexico, the Russian Federation, the United States and China.[14]
Reproductive mode
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The breeding of sea dogs is very unique. In May every year, male sea dogs take the lead in coming to the breeding place to seize the territory.Three to four weeks later, the female sea dog to be delivered came slowly and entered the male sea dog possession. The female sea dog who came near was immediately taken as a wife by the male sea dog who had been waiting for a long time.The number of female sea dogs owned by each male sea dog is very different. Some male sea dogs are alone, only with one female sea dog;Some male seals can be with more than 50 or even 100 female seals.The pregnant female seal will give birth to her only child on land within 1-5 days after her arrival.Just after giving birth to her pups, the female seal begins to have estrus again and mate with the male seal.After the stage of fertilization and polygamy, the female seal leaves here in autumn and leaves for the wintering place.After fertilization, the embryos of female sea dogs sometimes develop in the right corner of the uterus, and sometimes in the left corner, which is why female sea dogs can mate again immediately after childbirth.[15]
Every spring, sea dogs come to the colony on the beach or island to mate and give birth.the pacific oceanBeihaigouThe colony ofCommanders' Islands On.Interestingly, each seal will return to the island where it was born to look for a mate.They find the right island through the position of the sun and the smell of the sea water.
The male seal usually arrives at the colony at the end of May.They will roar and fight for territory.If the roaring fails to drive the other side away, they will attack each other and fight hard, but most of them will not fight to death.After the territorial dispute subsided, the female seal arrived at the colony, which was about the beginning of July.After landing, they will each join a male sealMonogynyGroup.There are at least 3 female seals and at most 40 female seals in this group.After mating, female seals will give birth in the second year.[15]
Female sea dogs begin to have reproductive ability at the age of 5, and then they usually give birth every year until they are 25 years old.Their life span may be more than 40 years.
The pregnancy period of seal is 12 months, but the embryo does not develop in the first 5 months after fertilization.This ensures that the pups can be born in the colony rather than in the sea.Normally, a female seal gives birth to one litter per litter, but occasionally she gives birth to two pups per litter.The newborn pup weighs about 5-6 kg, is weak and can't swim.The fur is black.Their mother must go to the sea to hunt for food after taking care of them for a day or two to recover her strength.Later, the female seal will come back to take care of the young for many days, and then go to the sea again to hunt.This pattern will last for 4 to 6 weeks.Female seals identify their pups by smell and sound, and return to their side.In this way, after three months, the pups can go to the sea alone to make a living.
Every year, about half of seal pups die soon after birth.Some were trampled to death by other seals in the colony, others died of hookworm disease or other infections.[4]
Population status
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The seal is an endangered animal recognized by the World Wildlife Conservation Association。[5]
