Origin of the species and description
Photo: Elephant seal
The elephant seal is a deep-sea diver, a long-distance traveler, and an animal that fasts for long periods of time. Elephant seals are extraordinary, coming together on land to give birth, mate and moult, but at sea they are solitary. Enormous demands are placed on their appearance in order to continue their lineage. Research shows that elephant seals are the children of a dolphin and a platypus or a dolphin and a koala.
Video: Elephant seal
Fun fact: These massive pinnipeds are not called elephant seals because of their size. They got their name from their inflatable faces that look like an elephant's trunk.
The history of the development of the elephant seal colony began on November 25, 1990, when less than two dozen individuals of these animals were counted in a small bay south of the Piedras Blancas lighthouse. In the spring of 1991, almost 400 seals were bred. In January 1992, the first birth occurred. The colony grew at a phenomenal pace. In 1993, about 50 cubs were born. In 1995, another 600 cubs were born. The population explosion continued. By 1996, the number of cubs born had increased to almost 1,000, and the colony extended all the way to the beaches along the coastal highway. The colony continues to expand today. In 2015, there were 10,000 elephant seals.
Population and species status
At one time, there was active fishing for elephant seals, as people were attracted to the meat of these animals, fat, and also wool. Both northern and southern species at one time found themselves on the verge of extinction. In 1892, elephant seals were thought to have completely disappeared from the face of the earth. Despite such assumptions, in 1910, one colony was identified within the island of Guadalupe, near lower California. After some time, closer to our time, based on new environmental laws, elephant seals were protected, which led to a positive result.
Nowadays, elephant seals are not considered an endangered species. Any hunting of these animals is prohibited, although they often end up in fishing nets and also die from collisions with boats. Their numbers are such that the IUCN has classified elephant seals as a species of “least concern.”
Appearance and features
Photo: What does an elephant seal look like?
Elephant seals are sociable animals belonging to the family Phocidae. The northern elephant seal is yellowish or gray-brown, while the southern elephant seal is blue-gray. The southern species has an extensive molting period, during which significant areas of hair and skin are lost. Males of both species reach a length of about 6.5 meters (21 ft) and a weight of about 3,530 kg (7,780 lb) and grow much larger than the females, which sometimes reach 3.5 meters and weigh 900 kg.
Elephant seals reach speeds of 23.2 km/h. The largest pinniped species of the 33 existing species is the southern elephant seal. Males can be over 6 meters in length and weigh up to 4.5 tons. Harbor seals have a wide, round face with very large eyes. The cubs are born with a black coat that sheds around the time of weaning (28 days), being replaced by a smooth, silver-gray coat. Within a year the coat will turn silver-brown.
Female elephant seals first give birth at around 4 years of age, although the range ranges from 2 to 6 years. Females are considered physically mature at age 6. Males reach sexual maturity at around 4 years of age, when the nose begins to grow. The nose is a secondary sexual characteristic, like a man's beard, and can reach an astonishing length of half a meter. Males reach physical maturity at about 9 years of age. The main breeding age is 9-12 years. Northern elephant seals live on average 9 years, while southern ones live from 20 to 22 years.
Humans shed hair and skin all the time, but elephant seals go through a catastrophic molt, in which the entire layer of epidermis with the hairs attached sticks together at one point in time. The reason for this sudden molting is that at sea they spend most of their time in cold, deep water. During the dive process, blood moves away from the skin. This helps them conserve energy and not lose body heat. Animals come to land while molting so that blood can circulate through the skin to help grow a new layer of epidermis and hair.
Where does the elephant seal live?
Photo: Southern elephant seal
There are two types of elephant seals:
- northern;
- southern.
Northern elephant seals are found in the North Pacific Ocean from Baja California, Mexico to the Gulf of Alaska and the Aleutian Islands. During the breeding season, they live on beaches on offshore islands and in a few remote locations on the mainland. During the rest of the year, with the exception of molting periods, elephant seals live far from the coast (up to 8000 km), usually descending to depths of more than 1500 meters below the ocean surface.
Southern elephant seals (Mirounga leonina) live in sub-Antarctic and cold Antarctic waters. They are distributed throughout the Southern Ocean around Antarctica and on most sub-Antarctic islands. The population is concentrated on the Antipodes Islands and Campbell Island. In winter they often visit Auckland, Antipodes and Snares Islands, less frequently Chatham Islands and sometimes various mainland areas. Southern elephant seals occasionally visit local coastlines on mainland New Zealand.
On the mainland, they can remain in the area for several months, giving people the opportunity to observe animals that normally live in sub-Antarctic waters. The grace and speed of such large marine mammals can be an impressive sight, and young seals can be very playful.
Fun fact: Unlike most other marine mammals (such as whales and dugongs), elephant seals are not entirely aquatic: they emerge from the water to rest, molt, mate, and give birth to their young.
Spreading
Large colonies of the southern elephant seal are located on the following subantarctic archipelagos and islands: South Georgia, Kerguelen, Heard, Macquarie. Outside the mating season, individual individuals can be found on the coasts of South Africa, Australia, New Zealand, Patagonia and Antarctica. These animals can cover sea distances of up to 4,800 km.
The northern elephant seal used to be distributed along the entire west coast of North America from Alaska to Baja California. In the 19th century, however, mass extermination of these animals began for the sake of blubber. Every year, thousands of elephant seals became victims of hunters and soon this species began to be considered extinct. Only one small colony of less than a hundred individuals survived on the Mexican island of Guadalupe. After her discovery, northern elephant seals were taken under protection.
In the 1930s, elephant seals came onto land to mate on California's Channel Islands. Northern elephant seals are now found on many islands along the western coast of the continent. In the north, their range reaches the Farallon Islands, and outside the mating season even to Vancouver Island.
The population increases by 15% every year and today this species is no longer seriously threatened. However, the fact that northern elephant seals have gone through a population bottleneck has resulted in extremely low genetic diversity among living individuals, which could become a serious problem under changing environmental conditions.
What does an elephant seal eat?
Photo: Female elephant seal
Elephant seals are carnivores. Southern elephant seals are open ocean predators and spend most of their time at sea. They feed on fish, squid or other cephalopods found in Antarctic waters. They come ashore only to breed and moult. The rest of the year is spent feeding in the sea, where they rest by swimming on the surface and diving in search of large fish and squid. While at sea they are often taken far from their breeding grounds and can travel very long distances between times spent on land.
It is believed that their females and males feed on different prey. The female diet mainly consists of squid, while the male diet is more varied, consisting of small sharks, rays and other bottom-dwelling fish. In search of food, males travel along the continental shelf to the Gulf of Alaska. Females tend to head north and west into the more open ocean. The elephant seal makes this migration twice a year, also returning to the rookery.
Elephant seals migrate in search of food, remain at sea for months, and often dive deep in search of food. In winter, they return to their rookeries to breed and give birth. Although male and female elephant seals spend time at sea, their migration routes and feeding habits differ: males follow a more consistent route, hunting along the continental shelf and foraging on the ocean floor, while females vary their routes in search of moving prey and They hunt more in the open ocean. Lacking echolocation, elephant seals use their vision and their whiskers to sense nearby movement.
Reproduction and lifespan
Immediately after molting, it is time for love in the life of elephants. From mid-winter to mid-spring, elephants fight, then breed, and raise their future offspring.
It all starts with the elephants crawling onto the shore. The female has been pregnant since last year. After all, this period covers eleven months. Male elephants have nothing to do with raising their offspring.
Having found a quiet, inconspicuous place, the mother gives birth to only one calf. He is born one meter tall and weighs up to forty kilograms. For a whole month, the mother elephant feeds the child only with her milk. Representatives of these individuals have the highest calorie content. Its fat content is fifty percent. The baby gains weight well during feeding. Afterwards, the mother leaves her child forever.
The offspring developed a sufficient layer of subcutaneous fat so that they could survive in the next adaptive, independent month of their lives. At three months of age, children leave the rookeries and go to open waters.
As soon as the female leaves her child, a period of mating fights without rules begins. The largest and oldest elephants fight to the death for the right to become the sultan of their harem.
Elephants roar loudly at each other, inflate their trunks and wave them, in the hope that this will scare the opponent. Then powerful, sharp teeth come into play. The winner gathers the ladies around him. Some people have harems of three hundred females. And the victim, all wounded, goes to the edge of the rookery. He still finds his soul mate, without the authority of a hyper-male. It’s unfortunate, but during such fights, very often small children suffer and die; they are simply not noticed in battle and are trampled by adults.
Having gathered his women, the leader chooses his passion, menacingly placing his front flipper on her back. This is how he shows superiority over her. And if the lady is not inclined to meet, the male does not care about this circumstance. He climbs all his tons onto her back. Here resistance is already useless.
The sexually mature period begins in the younger generation already at the age of four in males. Females, from the age of two, are ready for mating. Over the course of ten years, female elephant seals can give birth to children. Then they get old. Elephant seals die at fifteen or twenty years of age.
Features of character and lifestyle
Photo: Elephant seal in nature
Elephant seals come ashore and form colonies for just a few months each year to give birth, breed, and molt. During the rest of the year, the colonies disperse and individuals spend most of their time searching for food, which involves swimming thousands of miles and diving to great depths. While elephant seals are at sea in search of food, they dive to incredible depths.
They usually dive to a depth of about 1500 meters. The average dive duration is 20 minutes, but they can dive for an hour or longer. When elephant seals come to the surface, they spend only 2-4 minutes on land before diving back into the water - and continue this diving procedure 24 hours a day.
On land, elephant seals often remain without water for long periods of time. To avoid dehydration, their kidneys may produce concentrated urine, which contains more waste and less actual water in each drop. The rookery is a very noisy place during the breeding season as males vocalize, babies call to feed, and females squabble with each other over prime location and babies. Grunts, snorts, belches, whimpers, creaks, squeals and male roars combine to create a symphony of elephant seal sound.
Lifestyle
Elephant seals spend most of their lives underwater, feeding on fish and shellfish. They are able to dive to a depth of about 1400 meters, holding their breath for more than two hours. At the same time, the activity of their internal organs slows down, which saves the necessary amount of oxygen. Their natural enemies are killer whales and white sharks, which wait for long-nosed seals in the upper layers of the water.
Elephant seals come ashore only in the warm season in order to give birth to offspring and conceive new ones. For three whole months, huge colonies fill the coastal zones. Two to three dozen females give birth to babies under the protection of one male.
Fierce battles are fought for the harems, in which opponents are capable of inflicting serious injuries on each other. Every year, additional scars appear on the body of the strongest and largest males.
It is interesting that outwardly clumsy and clumsy elephant seals literally change before our eyes during fights. Sometimes they even straighten up to their full gigantic height and, vigorously waving their straightened trunk and hindquarters, perform amazing pirouettes.
Young three- to four-year-old elephant seals are forced to lead a bachelor lifestyle - they are pushed out of the edges of the colony by their more mature eight-year-old brothers. Considering this state of affairs to be unfair, they from time to time try to break through to the “married” females, which leads to new fights.
In harems, their own family life is in full swing. Each “wife” gives birth to one cub, about 80 cm long and weighing 20 kg. His mother feeds him nutritious milk for 4-5 weeks, after which he must fend for himself. After leaving it, he remains on the shore for another month, extracting nutrients from the fat layer. During this period, molting occurs, after which the baby goes on its first voyage.
The female is ready for a new fertilization approximately a month after giving birth. Her pregnancy will last a long 11 months. Having conceived, she fattens up a little at sea, and then goes to bed for the post-nuptial molt. Mature males are the last to molt.
Interestingly, during this period, animals of all ages relax so much that you can approach them closely. The body of seals resembles spread jelly, they absolutely do not pay attention to what is happening around them. Having finished their “land” affairs, elephant seals go to the ocean.
Social structure and reproduction
Photo: Baby elephant seal
Southern elephant seals, like northern elephant seals, breed and molt on land, but winter at sea, possibly near pack ice. Southern elephant seals breed on land but spend the winter in the cold Antarctic waters near the Antarctic ice. The northern species does not migrate during the breeding process. When breeding season arrives, male elephant seals define and defend territories and become aggressive towards each other.
They collect a harem of 40 to 50 females, which are much smaller than their huge partners. Males fight each other for mating dominance. Some encounters end in roars and aggressive posturing, but many others turn into brutal and bloody battles.
The breeding season begins at the end of November. Females begin to arrive in mid-December and continue to arrive until mid-February. The first birth occurs around Christmas, but most births usually occur in the last two weeks of January. Females remain on the beach for about five weeks after coming ashore. Surprisingly, males stay on the beach for up to 100 days.
When feeding with milk, females do not eat - both mother and child live off the energy accumulated in sufficient reserves of her fat. Both males and females lose about 1/3 of their weight during the breeding season. Females give birth to one cub each year after an 11-month pregnancy.
Fun fact: When a female gives birth, the milk she produces is about 12% fat. Two weeks later, this number increases to more than 50%, giving the liquid a pudding-like consistency. In comparison, cow's milk contains only 3.5% fat.
Reproduction
Animals begin to arrive at the rookeries at the beginning of spring. This is the end of August - the first ten days of September (in the southern hemisphere, summer begins in December and winter in June). First, pregnant females appear on the rocky shores. The males arrive later. Fights immediately begin between them. Sometimes they turn into whole bloody battles, since elephant seals have quite powerful front fangs.
In the end, everything calms down, and each male finds a harem. It can include 10 females, or a hundred. It all depends on the strength and aggression of the male. The birth of babies occurs in September and October. Females crawl away to give birth in secluded places. The cub is born alone. Its body length reaches up to a meter, and its weight is 25-30 kg.
The mother feeds the baby with milk for a month. Then she returns to the male and becomes pregnant again. The gestation period is 11 months, that is, almost a year. The baby is left alone. He is already getting married without his mother's supervision. When he is 3 months old, he swims with his peers into the open ocean. After molting, at the end of February, adult animals leave the rookery until next spring. Sexual maturity in males occurs at 4 years, in females at 2 years. The female gives birth every year for 10-12 years. These animals live on average 20 years.
Another enemy is man. In past centuries, he mercilessly destroyed harmless animals for their fat. From one killed elephant seal they received at least 500 kg of valuable product. Nowadays, fishing for these marine animals is prohibited. In this regard, their number has increased. The number of southern elephant seals today is 750 thousand. At least 250 thousand animals live on the island of South Georgia, and the same number on the Kerguelen Islands. These are the largest rookeries of huge seals, which they share with penguins.
The belonging of elephant seals to true seals today is indisputable, but their position within this taxon is often the subject of debate. King hypothesized in 1983 that elephant seals are most closely related to the monk seal genus and that both genera represent the most ancient forms of true seals. In 1996, Binida-Emodnes and Russell could not find evidence for such a close relationship, but they confirmed the basic position of elephant seals in the taxonomy of true seals.
Natural enemies of elephant seals
Photo: Elephant seal
Great southern elephant seals have few enemies, including:
- killer whales, which can hunt pups and old seals;
- leopard seals, which sometimes attack and kill pups;
- some large sharks.
Elephant seals can also be considered enemies of members of their population during breeding. Elephant seals form harems in which the dominant, or alpha, male is surrounded by a group of females. On the periphery of the harem, beta males wait in hopes of an opportunity to mate. They help the alpha male hold off less dominant males. Male-male wrestling can be a bloody affair, with males getting to their feet and slamming themselves against each other, slashing with large canine teeth.
Elephant seals use their teeth during combat to rip the necks of their opponents. Large males can be severely injured from fighting with other males during the breeding season. Fights between dominant males and challengers can be long, bloody and extremely brutal, with the loser often suffering serious injuries. However, not all confrontations end in battle. Sometimes all they have to do is rear up on their hind legs, throw back their heads, boast about the size of their noses and roar threats to intimidate most opponents. But when battles occur, it rarely comes to death.
Interesting Facts
- The amazing ability of elephant seals is to sleep underwater. But how do animals manage to breathe at this time? After all, they have lungs, not gills!.. Scientists managed to figure out the secret of such underwater sleep. After five or ten minutes under water, the animal’s chest expands, but the nostrils remain tightly closed. As a result, the density of the body decreases and it floats up. At the surface of the water, the nostrils open and the animal inhales air for about three minutes. Then it sinks to the bottom again. The eyes remain closed all this time: the elephant is clearly sleeping.
- Stones are commonly found in the elephant seal's stomach. Residents of the places where these animals live believe that the stones serve as ballast while the elephants dive under water. There are other explanations. For example, stones in the stomach can contribute to the grinding of food - whole swallowed fish and crustaceans.
- Among the males, four groups can be clearly distinguished. The first - “teenage” - includes animals aged from one to six years, their size does not exceed three meters. They appear at the rookery in winter, especially after storms, with the obvious purpose of taking a break from swimming. These animals appear before anyone else to molt - in December (the beginning of summer in the southern hemisphere), and then all other animals appear in order of seniority: the older they are, the later. The second, or “youthful” group is formed by animals aged from six to thirteen years, their size is from three to four and a half meters. They swim to the beach in the fall, soon after the females give birth to their cubs, but they do not engage in fights with older males and swim out to sea even before the start of the rut (after the cubs are weaned). The next age group is the so-called applicants. Such males, measuring from four and a half to six meters, with a proudly inflating trunk, are in a constantly aggressive mood and try to fight with the owners of the rookery - the owners of the “harems” - powerful old males, trying to take away some of the females from them. These old, experienced males make up the fourth age group.
- Observations have shown that the same old and strong male dominates the “harem” throughout the entire breeding season, and younger and weaker males are often forced to give up their place to a rival that is superior in strength. Although male fights usually take place in the water, not far from the shore, panic also begins on the beach at this time - alarmed females scream, the cubs try to escape. Therefore, from “harems” where they are too often disturbed, females try to move to calmer “harems”.
- The fight between males is an impressive spectacle. The rivals, having swam up to each other, rear up, rising about four meters above the shallow water, and freeze in this position for several minutes, reminiscent of stone sculptures of monsters. The animals emit a dull roar, their trunks swell menacingly, showering the enemy with a cascade of spray. After such a performance, the weaker enemy usually retreats backwards, continuing to roar threateningly, and, having moved to a safe distance, takes off running. The winner lets out a proud cry and, after making several false throws after the fugitive, calms down and returns to the beach.
- No matter how terrifying such a battle may look from the outside, in most cases it does not lead to serious bloodshed. Usually everything is limited to mutual intimidation, terrifying roars and sniffles. The biological meaning of this behavior is clear: the strongest is identified, who will take on the functions of a producer during the mating season and, as a continuer of the family, will pass on its positive qualities to the offspring. At the same time, the weaker young male does not die on the battlefield and thus is not excluded from the further process of reproduction of the species.
- Tall males do not always show aggressiveness towards humans. And it is not they, but the females that may turn out to be the most dangerous for a researcher who dares to penetrate into the very thick of the herd. John Warham, for example, more than once had to get acquainted with their sharp teeth and run away shamefully, leaving a good piece of his trouser leg as a souvenir to the angry elephant seal.
- Having been born, the cub emits a short bark, reminiscent of a dog, and the mother responds in kind, sniffs it and thus remembers it. Subsequently, she will unmistakably distinguish him among many other cubs and will be able to return him if he tries to escape.
- It is worth mentioning one of the most amazing adaptations of the animal body to the conditions of existence: the development of the embryo in the womb of the female is suspended during molting, and the embryo is, as it were, “preserved” for the entire unfavorable period of the animal’s life. (A similar phenomenon is observed in some other animals - many pinnipeds, as well as in sable, rabbit, kangaroo, etc.) The development of the embryo continues only in March, when the molting of females is already completed.
- The molting elephant seal looks most deplorable: its old skin hangs on it in torn rags. First it comes off the muzzle, and then from the rest of the body. At the same time, the poor creatures scratch their sides and stomach with their flippers, trying to speed up this obviously unpleasant process for them. Shedding animals usually settle down in some moss-covered swamp, not far from the shore, and, restlessly tossing and turning, stir up the loose soil, turning it into a dirty mess. They plunge into it up to their nostrils. The stench around at this time is terrifying.
