Pinniped презентация

Pinniped

Pinnipeds, commonly known as seals, are a widely distributed and diverse clade of carnivorous, fin-footed, semiaquatic marine mammals. They comprise the extant families Odobenidae (whose only living member is the walrus), Otariidae (the eared seals: sea lions and fur seals), and Phocidae (the earless seals, or true seals). There are 33 extant species of pinnipeds, and more than 50 extinct species have been described from fossils. While seals were historically thought to have descended from two ancestral lines, molecular evidence supports them as a monophyletic lineage (descended from one ancestral line). Pinnipeds belong to the order Carnivora; their closest living relatives are bears and the superfamily of musteloids (weasels, raccoons, skunks, and red pandas), having diverged about 50 million years ago.
Seals range in size from the 1 m and 45 kg Baikal seal to the 5 m and 3,200 kg southern elephant seal male, which is also the largest member of the order Carnivora. Several species exhibit sexual dimorphism. They have streamlined bodies and four limbs that are modified into flippers. Though not as fast in the water as dolphins, seals are more flexible and agile. Otariids use their front limbs primarily to propel themselves through the water, while phocids and walruses use their hind limbs. Otariids and walruses have hind limbs that can be pulled under the body and used as legs on land. By comparison, terrestrial locomotion by phocids is more cumbersome. Otariids have visible external ears, while phocids and walruses lack these.

Pinnipeds have well-developed senses—their eyesight and hearing are adapted for both air and water, and they have an advanced tactile system in their whiskers or vibrissae. Some species are well adapted for diving to great depths. They have a layer of fat, or blubber, under the skin to keep warm in the cold water, and, other than the walrus, all species are covered in fur.
Although pinnipeds are widespread, most species prefer the colder waters of the Northern and Southern Hemispheres. They spend most of their lives in the water, but come ashore to mate, give birth, molt or escape from predators, such as sharks and killer whales. They feed largely on fish and marine invertebrates; a few, such as the leopard seal, feed on large vertebrates, such as penguins and other seals. Walruses are specialized for feeding on bottom-dwelling mollusks. Male pinnipeds typically mate with more than one female (polygyny), although the degree of polygyny varies with the species. The males of land-breeding species tend to mate with a greater number of females than those of ice breeding species. Male pinniped strategies for reproductive success vary between defending females, defending territories that attract females and performing ritual displays or lek mating. Pups are typically born in the spring and summer months and females bear almost all the responsibility for raising them. Mothers of some species fast and nurse their young for a relatively short period of time while others take foraging trips at sea between nursing bouts. Walruses are known to nurse their young while at sea. Seals produce a number of vocalizations, notably the barks of California sea lions, the gong-like calls of walruses and the complex songs of Weddell seals.

Ringed seal

The ringed seal is an earless seal inhabiting the Arctic and sub-Arctic regions. The ringed seal is a relatively small seal, rarely greater than 1.5 m in length, with a distinctive patterning of dark spots surrounded by light grey rings, hence its common name. It is the most abundant and wide-ranging ice seal in the Northern Hemisphere, ranging throughout the Arctic Ocean, into the Bering Sea and Okhotsk Sea as far south as the northern coast of Japan in the Pacific and throughout the North Atlantic coasts of Greenland and Scandinavia as far south as Newfoundland, and including two freshwater subspecies in northern Europe. Ringed seals are one of the primary prey of polar bears and killer whales, and have long been a component of the diet of indigenous people of the Arctic.
Ringed seals are the smallest and most abundant member of the seal family that live in the Arctic and Sub-Arctic regions. The average life span of a ringed seal is 40 years, with a diet based mainly on Arctic cod and planktonic crustaceans. Typically about 1.5 metres long, the ringed seal is known to be solitary with their main predator being polar bears. Recently, however, the biggest threat to ringed seals has been the changing temperature in the Arctic and the detrimental changes to sea ice that follow. With declines in snowpack and sea ice due to warming ocean and atmospheric temperatures, survival has become tougher for ringed seals in the Arctic and Sub-Arctic regions. Yet ringed seals are also potentially projected to thrive due to warming, considering the early extinction of their predators. Climate change is sure to change the fate of all ringed seals in the coming years for better or worse.

The ringed seal is the smallest and most common seal in the Arctic, with a small head, short cat-like snout, and a plump body. Its coat is dark with silver rings on the back and sides with a silver belly, giving this seal its vernacular name. Depending on subspecies and condition, adult size can range from 100 to 175 cm and weigh from 32 to 140 kg. The seal averages about 5 ft long with a weight of about 50–70 kg. This species is usually considered the smallest species in the true seal family, although several related species, especially the Baikal seal, may approach similarly diminutive dimensions. Their small front flippers have claws more than 1 inch thick that are used to maintain breathing holes through 6.5 ft thick ice.
Ringed seals occur throughout the Arctic Ocean. They can be found in the Baltic Sea, the Bering Sea and the Hudson Bay. They prefer to rest on ice floe and will move farther north for denser ice. Two subspecies, P. h. saimensis and ladogensis, can be found in freshwater.
Ringed seals have a circumpolar distribution from approximately 35°N to the North Pole, occurring in all seas of the Arctic Ocean. In the North Pacific, they are found in the southern Bering Sea and range as far south as the seas of Okhotsk and Japan. Throughout their range, ringed seals have an affinity for ice-covered waters and are well adapted to occupying seasonal and permanent ice. They tend to prefer large floes (i.e., > 48 m in diameter) and are often found in the interior ice pack where the sea ice coverage is greater than 90%. They remain in contact with ice most of the year and pup on the ice in late winter-early spring.

Ringed seals are found throughout the Beaufort, Chukchi, and Bering Seas, as far south as Bristol Bay in years of extensive ice coverage. During late April through June, ringed seals are distributed throughout their range from the southern ice edge northward. Preliminary results from recent surveys conducted in the Chukchi Sea in May–June 1999 and 2000 indicate that ringed seal density is higher in nearshore fast and pack ice, and lower in offshore pack ice. Results of surveys conducted by Frost and Lowry indicate that, in the Alaskan Beaufort Sea, the density of ringed seals in May–June is higher to the east than to the west of Flaxman Island. The overall winter distribution is probably similar, and it is believed there is a net movement of seals northward with the ice edge in late spring and summer. Thus, ringed seals occupying the Bering and southern Chukchi seas in winter apparently are migratory, but details of their movements are unknown.
Ringed seals reside in arctic waters and are commonly associated with ice floes and pack ice. The ringed seal maintains a breathing hole in the ice thus allowing it to use ice habitat that other seals cannot.
Ringed seals eat a wide variety of small prey that consists of 72 species of fish and invertebrates. Feeding is usually a solitary behavior and their prey of choice includes mysids, shrimp, arctic cod, and herring. While feeding, ringed seals dive to depths of 35 to 150 ft. In the summer ringed seals feed along edge of the sea-ice for polar cod. In shallow water they feed on smaller cod. Ringed seals may also eat herring, smelt, whitefish, sculpin, perch, and crustaceans.

Baikal seal

The Baikal seal, Lake Baikal seal or nerpa, is a species of earless seal endemic to Lake Baikal in Siberia, Russia. Like the Caspian seal, it is related to the Arctic ringed seal. The Baikal seal is one of the smallest true seals and the only exclusively freshwater pinniped species. A subpopulation of inland harbour seals living in the Hudson Bay region of Quebec, Canada, the Saimaa ringed seal (a ringed seal subspecies) and the Ladoga seal (a ringed seal subspecies) are found in fresh water, but these are part of species that also have marine populations.
The most recent population estimates are 80,000 to 100,000 animals, roughly equaling the expected carrying capacity of the lake. At present, the species is not considered threatened.
The Baikal seal is one of the smallest true seals. Adults typically grow to 1.1–1.4 m in lengthwith a body mass from 63 to 70 kg. The maximum reported size is 1.65 m in length and 130 kg in weight. There are significant annual variations in the weight, with lowest weight in the spring and highest weight, about 38–42% more, in the fall. The animals show very little sexual dimorphism; males are only slightly larger than females. They have a uniform, steely-grey coat on their backs and fur with a yellowish tinge on their abdomens. As the coat weathers, it becomes brownish. When born, the pups weigh 3–3.5 kg and are about 70 cm long. They have coats of white, silky, natal fur. This fur is quickly shed and exchanged for a darker coat, much like that of adults. Rarely, Baikal seals can be found with spotted coats.

The Baikal seal lives only in the waters of Lake Baikal. It is something of a mystery how Baikal seals came to live there in the first place. They may have swum up rivers and streams or possibly Lake Baikal was linked to the ocean at some point through a large body of water, such as the West Siberian Glacial Lake or West Siberian Plain, formed in a previous ice age. The seals are estimated to have inhabited Lake Baikal for some two million years.
The areas of the lake in which the Baikal seals reside change depending on the season, as well as other environmental factors. They are solitary animals for the majority of the year, sometimes living kilometres away from other Baikal seals. In general, a higher concentration of Baikal seals is found in the northern parts of the lake, because the longer winter keeps the ice frozen longer, which is preferable for pupping. However, in recent years, migrations to the southern half of the lake have occurred, possibly to evade hunters. In winter, when the lake is frozen over, seals maintain a few breathing holes over a given area and tend to remain nearby, not interfering with the food supplies of nearby seals. When the ice begins to melt, Baikal seals tend to keep to the shoreline.

Caspian seal

The Caspian seal is one of the smallest members of the earless seal family and unique in that it is found exclusively in the brackish Caspian Sea. They are found not only along the shorelines, but also on the many rocky islands and floating blocks of ice that dot the Caspian Sea. In winter, and cooler parts of the spring and autumn season, these marine mammals populate the Northern Caspian. As the ice melts in the warmer season, they can be found on the mouths of the Volga and Ural Rivers, as well as the southern latitudes of the Caspian where cooler waters can be found due to greater depth.
Evidence suggests the seals are descended from Arctic ringed seals that reached the area from the north during an earlier part of the Quaternary period and became isolated in the landlocked Caspian Sea when continental ice sheets melted.
Adults are about 126–129 cm in length. Males are longer than females at an early age, but females experience more rapid growth until they reach ten years of age. Males can grow gradually until they reach an age of about 30 or 40 years. Adults weigh around 86 kg; males are generally larger and bulkier.
The skull structure of the Caspian seal suggests it is closely related to the Baikal seal. In addition, the morphological structures in both species suggest they are descended from the ringed seal which migrated from larger bodies of water around two million years ago.

Caspian seals are shallow divers, with diving depths typically reaching 50 m and lasting about a minute, although deeper and longer dives have been recorded, with at least one individual seen at depths in excess of 165 m. They are gregarious, spending most of their time in large colonies.
Caspian seals can be found not only along the shorelines, but also on the many rocky islands and floating blocks of ice that dot the Caspian Sea. As the ice melts in the warmer season, they can be found on the mouths of the Volga and Ural Rivers, as well as the southern latitudes of the Caspian where cooler waters can be found due to greater depth.
In winter, and cooler parts of the spring and autumn season, these marine mammals populate the Northern Caspian. In the first days of April, spring migration to the southern part of the Caspian Sea begins with mature female seals and their pups, during this migration hungry seals eat the fish in the nets. Male mature seals stay in the northern Caspian Sea longer and wait until the moulting is completed. In summer, seals find empty places in the western part of Apsheron for resting. In the eastern part, the most crowded place used to be the Ogurchinskiy Island, but by 2001, fewer than 10 pups were recorded on Ogurchinsky, some of which were killed by people on the island.

Spotted seal

The spotted seal, also known as the larga seal or largha seal, is a member of the family Phocidae, and is considered a "true seal". It inhabits ice floes and waters of the north Pacific Ocean and adjacent seas. It is primarily found along the continental shelf of the Beaufort, Chukchi, Bering and Okhotsk Seasand south to the northern Yellow Sea and it migrates south as far as northern Huanghai and the western Sea of Japan. It is also found in Alaska from the southeastern Bristol Bay to Demarcation Point during the ice-free seasons of summer and autumn when spotted seals mate and have pups. Smaller numbers are found in the Beaufort Sea. It is sometimes mistaken for the harbor seal to which it is closely related and spotted seals and harbor seals often mingle together in areas where their habitats overlap.
The spotted seal is of the family, Phocidae, or "true seals". Compared to other true seals, they are intermediate in size, with mature adults of both sexes generally weighing between 180 and 240 pounds and measuring 4.59 to 6.89 ft, roughly the same size as a harbor seal or ribbon seal. The head of a spotted seal is round, with a narrow snout resembling that of a dog.
The spotted seal has a relatively small body and short flippers extending behind the body that provide thrust, while the small flippers in front act as rudders. The dense fur varies in color from silver to gray and white and is characterized by dark, irregular spots against the lighter background and covering the entire body. Males and females differ little in size or shape. In places where their habitat overlaps with that of the harbor seal, they can be confused with them, as in Bristol Bay, Alaska. Like harbor seals, spotted seals have 34 teeth.

Spotted seals are inhabitants of arctic or sub-arctic waters, often in the outer areas of ice floes during the breeding season. They tend not to live within dense drift ice. In the summer months they live in the open ocean or on nearby shores.
Spotted seals are separated into three populations. The Bering Sea population includes approximately 100,000 in the western Bering Sea near Kamchatka, in the Gulf of Anadyr in Russia, and in the eastern Bering Sea in Alaskan waters (the only population in the US). A second population of about 100,000 seals breeds in the Sea of Japan and the Sea of Okhotsk. A third population of about 3,300 seals is to the south in Liaodong Bay, China and Peter the Great Bay, Russia. There is also a smaller population of 300 grey spotted seals living in waters off Baekryeong Island located far north of the west coast of South Korea.In order to prevent the squabble from being fought by water-bombing rocks on Baengnyeong Island, the Hani Sea Water Leopard Artificial Rest Area has been set up.

Harbor seal

The harbor (or harbour) seal, also known as the common seal, is a true seal found along temperate and Arctic marine coastlines of the Northern Hemisphere. The most widely distributed species of pinniped (walruses, eared seals, and true seals), they are found in coastal waters of the northern Atlantic, Pacific Oceans, Baltic and North Seas.
Harbor seals are brown, silvery white, tan, or gray, with distinctive V-shaped nostrils. An adult can attain a length of 1.85 m and a mass of up to 168 kg. Blubber under the seal's skin helps to maintain body temperature. Females outlive males (30–35 years versus 20–25 years). Harbor seals stick to familiar resting spots or haulout sites, generally rocky areas (although ice, sand, and mud may also be used) where they are protected from adverse weather conditions and predation, near a foraging area. Males may fight over mates under water and on land. Females bear a single pup after a nine-month gestation, which they care for alone. Pups can weigh up to 16 kg and are able to swim and dive within hours of birth. They develop quickly on their mothers' fat-rich milk, and are weaned after four to six weeks.
The global population of harbor seals is 350,000–500,000, but subspecies in certain habitats are threatened. Once a common practice, sealing is now illegal in many nations within the animal's range.

Individual harbor seals possess a unique pattern of spots, either dark on a light background or light on a dark. They vary in color from brownish black to tan or grey; underparts are generally lighter. The body and flippers are short, heads are rounded. Nostrils appear distinctively V-shaped. As with other true seals, there is no pinna (ear flap). An ear canal may be visible behind the eye. Including the head and flippers, they may reach an adult length of 1.85 meters and a weight of 55 to 168 kg. Females are generally smaller than males.
Harbor seals prefer to frequent familiar resting sites. They may spend several days at sea and travel up to 50 km in search of feeding grounds, and will also swim more than a hundred miles upstream into fresh water in large rivers in search of migratory fish like shad and likely salmon. Resting sites may be both rugged, rocky coasts, such as those of the Hebrides or the shorelines of New England, or sandy beaches, like the ones that flank Normandy in Northern France or the Outer Banks of North Carolina. Harbor seals frequently congregate in harbors, bays, sandy intertidal zones, and estuaries in pursuit of prey fish such as salmon, menhaden, anchovy, sea bass, herring, mackerel, cod, whiting and flatfish, and occasionally shrimp, crabs, mollusks, and squid. Atlantic subspecies of either Europe or North America also exploit deeper-dwelling fish of the genus Ammodytes as a food source and Pacific subspecies have been recorded occasionally consuming fish of the genus Oncorhynchus. Although primarily coastal, dives of over 500 m have been recorded. Harbor seals have been recorded to attack, kill and eat several kinds of ducks.

Grey seal

The grey seal is found on both shores of the North Atlantic Ocean. It is a large seal of the family Phocidae, which are commonly referred to as "true seals" or "earless seals". It is the only species classified in the genus Halichoerus. Its name is spelled gray seal in the US; it is also known as Atlantic seal and the horsehead seal.
This is a fairly large seal, with bulls in the eastern Atlantic populations reaching 1.95–2.3 m long and weighing 170–310 kg; the cows are much smaller, typically 1.6–1.95 m long and 100–190 kg in weight. Individuals from the western Atlantic are often much larger, with males averaging up to 2.7 m and reaching a weight of as much as 400 kg and females averaging up to 2.05 m and sometimes weighing up to 250 kg. Record-sized bull grey seals can reach about 3.3 m in length. A common average weight in Great Britain was found to be about 233 kg for males and 154.6 kg for females whereas in Nova Scotia, Canada adult males averaged 294.6 kg and adult females averaged 224.5 kg. It is distinguished from the smaller harbor seal by its straight head profile, nostrils set well apart, and fewer spots on its body. Wintering hooded seals can be confused with grey seals as they are about the same size and somewhat share a large-nosed look but the hooded has a paler base colour and usually evidences a stronger spotting. Grey seals lack external ear flaps and characteristically have large snouts. Bull greys have larger noses and a less curved profile than harbor seal bulls. Males are generally darker than females, with lighter patches and often scarring around the neck. Females are silver grey to brown with dark patches.

The grey seal feeds on a wide variety of fish, mostly benthic or demersal species, taken at depths down to 70 m or more. Sand eels are important in its diet in many localities. Cod and other gadids, flatfish, herring, wrasse and skates are also important locally. However, it is clear that the grey seal will eat whatever is available, including octopus and lobsters. The average daily food requirement is estimated to be 5 kg, though the seal does not feed every day and it fasts during the breeding season.
Recent observations and studies from Scotland, The Netherlands and Germany show that grey seals will also prey and feed on large animals like harbour seals and harbour porpoises. In 2014, a male grey seal in the North Sea was documented and filmed killing and cannibalising 11 pups of his own species over the course of a week. Similar wounds on the carcasses of pups found elsewhere in the region suggest that cannibalism and infanticide may not be uncommon in grey seals. Male grey seals may engage in such behaviour potentially as a way of increasing reproductive success through access to easy prey without leaving prime territory.

Ribbon seal

The ribbon seal is a medium-sized pinniped from the true seal family. A seasonally ice-bound species, it is found in the Arctic and Subarctic regions of the North Pacific Ocean, notably in the Bering Sea and Sea of Okhotsk. It is distinguished by its striking coloration, with two wide white strips and two white circles against dark brown or black fur.
Adult seals are recognizable by their black skin, which carries four white markings: a strip around the neck, one around the tail and a circular marking on each body side, which encloses the front fins. The contrast is particularly strong with the males, while with females the difference in color between bright and dark portions is often less conspicuous. Newborn ribbon seal pups have white natal fur. After moulting their natal fur, their color changes to blue-grey on their backs and silvery beneath. Over the course of three years, portions of the fur become darker and others brighter after every molt, and only at the age of four years does the striped pattern emerge.
The ribbon seal has a short snout with broad, deep internal nares and large, rounded, front-facing orbits. Like other phocids it possess enlarged auditory bullae and lacks a sagittal crest. The ribbon seal has curved, widely spaced dentition and smaller canines than other species of phocid.

The ribbon seal has a large inflatable air sac that is connected to the trachea and extends on the right side over the ribs. It is larger in males than in females, and it is thought that it is used to produce underwater vocalizations, perhaps for attracting a mate. Unlike other pinnipeds, the ribbon seal lack lobes in its lungs that divide the lungs into smaller compartments. The ribbon seal can grow about 1.6 m long, weighing 95 kg in both sexes.
The main predators of ribbon seals include Great white sharks and Killer whales.
Ribbon seals are rarely seen out on the ice and snow. Their method of movement on the ice is highly specialized. While quickly undulating their body in serpentine motion, they grip into the ice with their claws and use alternating flipper strokes to pull themselves across the ice's surface. It has been observed that this form of locomotion is rendered ineffective on other surfaces, most likely due to the increased friction between the animal's fur and the substrate.
The diet of ribbon seal consists almost exclusively of pelagic creatures: fish like pollocks, eelpouts, the Arctic cod and cephalopods such as squid and octopus; young seals eat crustaceans as well. The ribbon seal dives to depths of up to 200 m in search of food; it is solitary and forms no herds.
Ribbon seals located in the Bering Sea consume pollock, eelpout, and arctic cod. Adult seals have relatively weak and smooth canines because their food does not need to be viciously torn.

Harp seal

The harp seal, also known as saddleback seal or Greenland seal, is a species of earless seal, or true seal, native to the northernmost Atlantic Ocean and Arctic Ocean. Originally in the genus Phoca with a number of other species, it was reclassified into the monotypic genus Pagophilus in 1844. In Greek, its scientific name translates to "ice-lover from Greenland," and its taxonomic synonym, Phoca groenlandica translates to "Greenlandic seal.«
The mature harp seal has pure black eyes. It has a silver-gray fur covering its body, with black harp or wishbone-shaped markings dorsally. Adult harp seals grow to be 1.7 to 2.0 m long and weigh from 115 to 140 kg. The harp seal pup often has a yellow-white coat at birth due to staining from amniotic fluid, but after one to three days, the coat turns white and stays white for 2–3 weeks, until the first molt. Adolescent harp seals have a silver-gray coat spotted with black.
Like most pinnipeds, harp seals are carnivorous. They have a diverse diet including several dozen fish and invertebrate species. The White Sea population migrates northward in the summer to forage extensively in the Barents Sea, where common prey items include krill, capelin, herring, flat fish and Gadiform fish. Harp seals prefer some prey, though their diet depends largely on prey abundance. Diet and abundance analysis of the Svalbard population found that this population predominantly eats krill, followed closely by polar cod.

Some individuals from the Greenland Sea sub-population have foraged in the Barents Sea alongside the White Sea sub-population during late summer and fall. Barents Sea harp seals eat mostly herring and polar cod but less krill or amphipods, likely because these seals usually dive deeper than such prey.
Global harp seal population estimates total around 7.6 million individuals. The number of pups born in the traditional pupping area of the southern Gulf of St. Lawrence was greatly reduced, with an estimated pup production of only 18,300. Another 13,600 pups were born in the northern Gulf. An estimated 714,600 pups were born off the northeastern coast of Newfoundland (Front); accounting for 96% of all pupping in 2017. Combining the estimates from all areas resulted in an estimated total pup production of 746,500. Due to their dependence on pack ice for breeding, the harp seal range is restricted to areas where pack ice forms seasonally. The western North Atlantic stock, which is the largest, is located off eastern Canada. This population is further divided into two separate herds based on the breeding location. The Front herd breeds off the coast of Labrador and Newfoundland, and the Gulf herd breeds near the Magdalen Islands in the middle of the Gulf of St. Lawrence. A second stock breeds on the "West Ice" off eastern Greenland. A third stock breeds on the "East Ice" in the White Sea, which is off the north coast of Russia below the Barents ea. Breeding occurs between mid-February and April, and varies somewhat for each stock. The three stocks are allopatric and don't interbreed.

Hooded seal

The hooded seal is a large phocid found only in the central and western North Atlantic, ranging from Svalbard in the east to the Gulf of St. Lawrence in the west. The seals are typically silver-grey or white in color, with black spots that vary in size covering most of the body. Hooded seal pups are known as "blue-backs" because their coats are blue-grey on the back with whitish bellies, though this coat is shed after 14 months of age when the pups molt.
Hooded seals live primarily on drifting pack ice and in deep water in the Arctic Ocean and North Atlantic. Although some drift away to warmer regions during the year, their best survival rate is in colder climates. They can be found on four distinct areas with pack ice: near Jan Mayen Island (northeast of Iceland); off Labrador and northeastern Newfoundland; the Gulf of St. Lawrence; and the Davis Strait (off midwestern Greenland). Males appear to be localized around areas of complex seabed, such as Baffin Bay, Davis Strait, and the Flemish cap, while females concentrate their habitat efforts primarily on shelf areas, such as the Labrador Shelf. Hooded seals are known to be a highly migratory species that often wander long distances, as far west as Alaska and as far south as the Canary Islands and Guadeloupe. Prior to the mid 1990s, hooded seal sightings in Maine and the east Atlantic were rare, but began increasing in the mid 1990s. From January 1997 to December 1999, a total of 84 recorded sightings of hooded seals occurred in the Gulf of Maine, one in France and one in Portugal. From 1996 to 2006, five strandings and sightings were noted near the Spanish coasts in the Mediterranean Sea. There is no scientific explanation for the increase in sightings and range of the hooded seal.

Bearded seal

The bearded seal, also called the square flipper seal, is a medium-sized pinniped that is found in and near to the Arctic Ocean. It gets its generic name from two Greek words (eri and gnathos) that refer to its heavy jaw. The other part of its Linnaean name means bearded and refers to its most characteristic feature, the conspicuous and very abundant whiskers. When dry, these whiskers curl very elegantly, giving the bearded seal a "raffish" look.
Bearded seals are the largest northern phocid. They have been found to weigh as much as 300 kg with the females being the largest. However, male and female bearded seals are not very dimorphic.
Distinguishing features of this earless seal include square fore flippers and thick bristles on its muzzle. Adults are greyish-brown in colour, darker on the back; rarely with a few faint spots on the back or dark spots on the sides. Occasionally the face and neck are reddish brown. Bearded seal pups are born with a greyish-brown natal fur with scattered patches of white on the back and head. The bearded seal is unique in the subfamily Phocinae in having two pairs of teats, a feature it shares with monk seals.
Bearded seals reach about 2.1 to 2.7 m in nose-to-tail length and from 200 to 430 kg in weight. The female seal is larger than the male, meaning that they are sexually dimorphic.

Bearded seals, along with ringed seals, are a major food source for polar bears. They are also an important food source for the Inuit of the Arctic coast. The Inuit language name for the seal is ugjuk or oogrook or oogruk. The Inuit preferred the ringed seal for food and light; the meat would be eaten and the blubber burnt in the kudlik (stone lamp). The skin of the bearded seal is tougher than regular seal and was used to make shoes, whips, dog sled harnesses, to cover a wooden frame boat, the Umiak and in constructing summer tents known as tupiq.
The body fat content of a bearded seal is about 25–40%.
Bearded seals are extant in Arctic and sub-Arctic regions. In the Pacific region, they extend from the Chukchi Sea in the Arctic, south into the Bering Sea where they span from Bristol Bay on the Alaskan coast to the Sea of Okhotsk on the Russian coast, up to but not including the northern coast of Japan. In the Arctic Ocean, they are found along the northern coasts of Russia, Norway, Canada, and Alaska, including the Norwegian Archipelago of Svalbard and Canadian Arctic Archipelago. In the Atlantic, Bearded seals are found along the northern coast of Iceland, the east and west coasts of Greenland and the Canadian mainland as far south as Labrador.
Although the range typically only extends down into sub-arctic areas bearded seals have been seen in Japan and China, as well as extremely far south of their range in Germany, Netherlands, United Kingdom, France, Spain and Portugal.

Weddell seal

The Weddell seal is a relatively large and abundant true seal with a circumpolar distribution surrounding Antarctica. The Weddell seal was discovered and named in the 1820s during expeditions led by British sealing captain James Weddell to the area of the Southern Ocean now known as the Weddell Sea. The life history of this species is well documented since it occupies fast ice environments close to the Antarctic continent and often adjacent to Antarctic bases.
Weddell seals measure about 2.5–3.5 m long and weigh 400–600 kg. They are amongst the largest seals, with a rather bulky body and short fore flippers relative to their body length. Males weigh less than females, usually about 500 kg or less. Male and female Weddell seals are generally about the same length, though females can be slightly larger. However, the male seal tends to have a thicker neck and a broader head and muzzle than the female. A molecular genetic based technique has been established to confirm the sex of individuals in the laboratory. The Weddell seal face has been compared to that of a cat due to a short mouth line and similarities in the structure of the nose and whiskers.

The Weddell seal grows a thin fur coat around its whole body except for small areas around the flippers. The colour and pattern of the coat varies, often fading to a duller colour as the seal ages. This coat moults around the beginning of summer. Adults show a counter-shaded coloration that varies from bluish-black to dark gray dorsally and to light gray/silver ventrally. Coats may change to shades of brown before the annual molt. Adult males usually bear scars, most of them around the genital region. Weddell seal pups are born with a lanugo of similar coloration and they moult after 3–4 weeks; later, they turn a darker color similar to that of adults. The pups are around half the length of their mother at birth, and weigh 25–30 kg. They gain around 2 kg a day, and by 6–7 weeks old they can weigh around 100 kg.

Leopard seal

The leopard seal, also referred to as the sea leopard, is the second largest species of seal in the Antarctic (after the southern elephant seal). Its only natural predator is the killer whale. It feeds on a wide range of prey including cephalopods, other pinnipeds, krill, birds and fish. It is the only species in the genus Hydrurga. Its closest relatives are the Ross seal, the crabeater seal and the Weddell seal, which together are known as the tribe of Lobodontini seals. The name hydrurga means "water worker" and leptonyx is the Greek for "thin-clawed".
The leopard seal has a distinctively long and muscular body shape when compared to other seals, but it is perhaps best known for its reptilian-like head and massive jaws which are enormous for its body size and which allow it to be one of the top predators in its environment. The front teeth are sharp like those of other carnivores, but their molars lock together in a way that allows them to sieve krill from the water in the manner of the crabeater seal. The coat is counter-shaded with a silver to dark gray blend and a distinctive spotted "leopard" coloration pattern dorsally and a paler, white to light gray color ventrally. Females are slightly larger than males. The overall length of adults is 2.4–3.5 m and weight is from 200 to 600 kilograms making them the same length as the northern walrus but usually less than half the weight. The whiskers are short and clear.
As "true" seals, they do not have external ears or pinnae, but possess an internal ear canal that leads to an external opening. Their hearing in air is similar to that of a human, but scientists have noted that leopard seals use their ears in conjunction with their whiskers to track prey under water.

Leopard seals are pagophilic ("ice-loving") seals, which primarily inhabit the Antarctic pack ice between 50˚S and 80˚S. Sightings of vagrant leopard seals have been recorded on the coasts of Australia, New Zealand (where individuals have been seen even on the foreshores of major cities such as Auckland and Dunedin), South America, and South Africa. In August 2018, an individual was sighted at Geraldton, on the west coast of Australia. Higher densities of leopard seals are seen in the Western Antarctic than in other regions.
Most leopard seals remain within the pack ice throughout the year and remain solitary during most of their lives with the exception of a mother and her newborn pup. These matrilineal groups can move further north in the austral winter to sub-antarctic islands and the coastlines of the southern continents to provide care for their pups.

Crabeater seal

The crabeater seal, also known as the krill-eater seal, is a true seal with a circumpolar distribution around the coast of Antarctica. They are medium- to large-sized (over 2 m in length), relatively slender and pale-colored, found primarily on the free-floating pack ice that extends seasonally out from the Antarctic coast, which they use as a platform for resting, mating, social aggregation and accessing their prey. They are by far the most abundant seal species in the world. While population estimates are uncertain, there are at least 7 million and possibly as many as 75 million individuals. This success of this species is due to its specialized predation on the abundant Antarctic krill of the Southern Ocean, for which it has uniquely adapted, sieve-like tooth structure. Indeed, its scientific name, translated as "lobe-toothed (lobodon) crab eater", refers specifically to the finely lobed teeth adapted to filtering their small crustacean prey. Despite its name, crabeater seals do not eat crabs. As well as being an important krill predator, the crabeater seal's pups are an important component of the diet of leopard seals, which are responsible for 80% of all crabeater pups deaths.
Adult seals (over five years old) grow to an average length of 2.3 m and an average weight of around 200 kg. Females are on average 6 cm longer and around 8 kilograms heavier than males, though their weights fluctuate substantially according to season; females can lose up to 50% of their body weight during lactation, and males lose a significant proportion of weight as they attend to their mating partners and fight off rivals. During summer, males typically weigh 200 kilograms, and females 215 kilograms.

A molecular genetic based technique has been established to confirm the sex of individuals in the laboratory. Large crabeater seals can weigh up to 300 kg. Pups are about 1.2 metres in length and 20 to 30 kilograms at birth. While nursing, pups grow at a rate of about 4.2 kilograms a day, and grow to be around 100 kilograms when they are weaned at two or three weeks.
These seals are covered mostly by brown or silver fur, with darker coloration around flippers. The color fades throughout the year, and recently molted seals appear darker than the silvery-white crabeater seals that are about to molt. Their body is comparatively more slender than other seals, and the snout is pointed. Crabeater seals can raise their heads and arch their backs while on ice, and they are able to move quickly if not subject to overheating. Crabeater seals exhibit scarring either from leopard seal attacks around the flippers or, for males, during the breeding season while fighting for mates around the throat and jaw. Pups are born with a light brown, downy pelage (lanugo), until the first molt at weaning. Younger animals are marked by net-like, chocolate brown markings and flecks on the shoulders, sides and flanks, shading into the predominantly dark hind and fore flippers and head, often due to scarring from leopard seals. After molting, their fur is a darker brown fading to blonde on their bellies. The fur lightens throughout the year, becoming completely blonde in summer.

Elephant seal

The elephant seal is one of two species of elephant seals. It is the largest member of the clade Pinnipedia and the order Carnivora, as well as the largest extant marine mammal that is not a cetacean. It gets its name from its massive size and the large proboscis of the adult male, which is used to produce very loud roars, especially during the breeding season. A bull southern elephant seal is about 40% heavier than a male northern elephant seal, more than twice as heavy as a male walrus, and 6–7 times heavier than the largest living terrestrial carnivorans, the polar bear and the Kodiak bear.
Elephant seal size also varies regionally. Studies have indicated elephant seals from South Georgia are around 30% heavier and 10% longer on average than those from Macquarie Island. The record-sized bull, shot in Possession Bay, South Georgia, on 28 February 1913, measured 6.85 m long and was estimated to weigh 5,000 kg, although it was only partially weighed piecemeal. The maximum size of a female is 1,000 kg and 3.7 m.
Elephant seal's eyes are large, round, and black. The width of the eyes, and a high concentration of low-light pigments, suggest sight plays an important role in the capture of prey. Like all seals, elephant seals have hind limbs whose ends form the tail and tail fin. Each of the "feet" can deploy five long, webbed fingers.

This agile dual palm is used to propel water. The pectoral fins are used little while swimming. While their hind limbs are unfit for locomotion on land, elephant seals use their fins as support to propel their bodies. They are able to propel themselves quickly (as fast as 8 km/h) in this way for short-distance travel, to return to water, to catch up with a female, or to chase an intruder.
Pups are born with fur and are completely black. Their coats are unsuited to water, but protect infants by insulating them from the cold air. The first moulting accompanies weaning. After moulting, the coats may turn grey and brown, depending on the thickness and moisture of hair. Among older males, the skin takes the form of a thick leather which is often scarred.
Like other seals, the vascular system of elephant seals is adapted to the cold; a mixture of small veins surround arteries, capturing heat from them. This structure is present in extremities such as the hind legs.

Monk seal

The monk seal is a monk seal belonging to the family Phocidae. As of 2015, it is estimated that fewer than 700 individuals survive in three or four isolated subpopulations in the Mediterranean, (especially) in the Aegean Sea, the archipelago of Madeira and the Cabo Blanco area in the northeastern Atlantic Ocean. It is believed to be the world's rarest pinniped species.
This species of seal grows from approximately 80 centimetres long at birth up to an average of 2.4 metres as adults, females slightly shorter than males. Males weigh an average of 320 kilograms and females weigh 300 kilograms, with overall weight ranging from 240–400 kilograms. They are thought to live up to 45 years old; the average life span is thought to be 20 to 25 years old and reproductive maturity is reached at around age four.
The monk seals' pups are about 1 metre long and weigh around 15–18 kilograms, their skin being covered by 1–1.5 centimeter-long, dark brown to black hair. On their bellies, there is a white stripe, which differs in color and shape between the two sexes. In females the stripe is usually rectangular in shape whereas in males it is usually butterfly shaped. This hair is replaced after six to eight weeks by the usual short hair adults carry. Adults will continue to molt annually, causing their color vibrancy to change throughout the year.

Pregnant monk seals typically use inaccessible undersea caves while giving birth, though historical descriptions show they used open beaches until the 18th century. There are eight pairs of teeth in both jaws.
Believed to have the shortest hair of any pinniped, the Mediterranean monk seal fur is black (males) or brown to dark grey (females), with a paler belly, which is close to white in males. The snout is short broad and flat, with very pronounced, long nostrils that face upward, unlike their Hawaiian relative, which tend to have more forward nostrils. The flippers are relatively short, with small slender claws. Monk seals have two pairs of retractable abdominal teats, unlike most other pinnipeds.
Monk seals are diurnal and feed on a variety of fish and mollusks, primarily octopus, squid, and eels, up to 3 kg per day. Although they commonly feed in shallow coastal waters, they are also known to forage at depths up to 250 meters, with an average depth varying between specimens. Monk seals prefer hunting in wide-open spaces, enabling them to use their speed more effectively. They are successful bottom-feeding hunters; some have even been observed lifting slabs of rock in search of prey.

Fur seal

The fur seal, is one of eight seals in the genus Arctocephalus, and one of nine fur seals in the subfamily Arctocephalinae. Despite what its name suggests, the Antarctic fur seal is mostly distributed in Subantarctic islandsand its scientific name is thought to have come from the German vessel SMS Gazelle, which was the first to collect specimens of this species from Kerguelen Islands.
This fur seal is a midsized pinniped with a relatively long neck and pointed muzzle compared with others in the family. The nose does not extend much past the mouth, the external ears are long, prominent, and naked at the tip. Adults have very long vibrissae, particularly males, up to 35 to 50 cm. The fore flippers are about one-third, and hind flippers slightly more than one-fourth, of the total length. These seals find the antarctic warm so they take plunges in cold water to stay cold.
Adult males are dark brown in colour. Females and juveniles tend to be paler, almost grey with lighter undersides. Colour patterns are highly variable, and scientists reported that some hybridization between Subantarctic and Antarctic fur seals has occurred. Pups are dark brown at birth, almost black in color. About one in 1000 Antarctic fur seals are pale 'blonde' variants - not albino - and they stay so as adults.
Males are substantially larger than females. Males grow up to 2 m long and with a mean weigh of 133 kg. Females reach 1.4 m with a mean weight of 34 kg. At birth, mean standard length is 67.4cm and mass is 5.9kg in males and 5.4kg in females.
Antarctic fur seals live up to 20 years with a maximum observed for female of 24.

Sea lion

The sea lion, also called the Southern Sea Lion and the Patagonian sea lion, is a sea lion found on the Ecuadorian, Peruvian, Chilean, Falkland Islands, Argentinean, Uruguayan, and Southern Brazilian coasts. It is the only member of the genus Otaria. Its scientific name was subject to controversy, with some taxonomists referring to it as Otaria flavescens and others referring to it as Otaria byronia. The former eventually won out, although that may still be overturned. Locally, it is known by several names, most commonly lobo marino (sea wolf) and león marino and the hair seal.
The South American sea lion is perhaps the archetypal sea lion in appearance. Males have a very large head with a well-developed mane, making them the most lionesque of the eared seals. They are twice the weight of females. Both males and females are orange or brown coloured with upturned snouts. Pups are born greyish orange ventrally and black dorsally and moult into a more chocolate colour.
The South American sea lion's size and weight can vary considerably. Adult males can grow over 2.73 m and weigh up to 350 kg. Adult females grow up to 1.8–2 m and weigh about half the weight of the males, around 150 kg. This species is even more sexually dimorphic than the other sea lions.

Walrus

The walrus is a large flippered marine mammal with a discontinuous distribution about the North Pole in the Arctic Ocean and subarctic seas of the Northern Hemisphere. The walrus is the only living species in the family Odobenidae and genus Odobenus. This species is subdivided into two subspecies:the Atlantic walrus, which lives in the Atlantic Ocean, and the Pacific walrus, which lives in the Pacific Ocean.
Adult walrus are characterised by prominent tusks and whiskers, and their considerable bulk: adult males in the Pacific can weigh more than 2,000 kilograms and, among pinnipeds, are exceeded in size only by the two species of elephant seals. Walruses live mostly in shallow waters above the continental shelves, spending significant amounts of their lives on the sea ice looking for benthic bivalve mollusks to eat. Walruses are relatively long-lived, social animals, and they are considered to be a "keystone species" in the Arctic marine regions.
While some outsized Pacific males can weigh as much as 2,000 kg, most weigh between 800 and 1,700 kg. An occasional male of the Pacific subspecies far exceeds normal dimensions. In 1909, a walrus hide weighing 500 kg was collected from an enormous bull in Franz Josef Land, while in August 1910, Jack Woodson shot a 4.9-metre-long walrus, harvesting its 450 kg hide. Since a walrus's hide usually accounts for about 20% of its body weight, the total body mass of these two giants is estimated to have been at least 2,300 kg.