Seals are a widely distributed clade of fin-footed, semiaquatic marine mammals. They comprise the extant families Odobenidae (walrus), Otariidae (the eared seals: sea lions and fur seals), and Phocidae (the earless seals, or true seals).
The earless seals or true seals are found mainly in the cold seas of the world.
True seals include the grey seal whose main population is around British coast, and grows to 2.7 m 9 feet , also the shorter-nosed common seal found in coastal regions over much of the northern hemisphere.
The largest seal is the Southern elephant seal which can be 6 metres (20 feet) long and weighs as much as four and a half tonnes.
The smallest of the species is the Baikal seal, which is only 1.2 m 4 feet long, and is the only seal to live in entirely in freshwater.
Streamlined in body shape, seals have thick blubber insulation, no external ear flaps and small front flippers.
The hind flippers point backwards and are swung from side to side to provide a thrust for swimming, but unlike the sea lion, they cannot be bought under the body for walking on them. To "walk" on land, a seal has to wriggle with their front flippers and abdominal muscles.
Deprived of sight and hearing, seals can still accurately pinpoint the locations of fish because they have 1,500 nerve endings in their whiskers.
Seal pups gain between three and five pounds each day because their mothers’ milk contains 50 per cent fat.
A seal was once abandoned in her colony because was ginger. Born with rare brownish-red fur and wonky blue eyes, the unfortunate baby seal was rescued from a beach on Tyuleniy Island, in the Caspian Sea, after it was abandoned by its mother. The pup's color is the result of an accumulation of iron in its fur.
Seals are rampant carnivores – consuming up to five per cent of their body weight a day in fish, squid and scrustaceans.
Antarctic fur seals can eat about a ton of fish and krill a year – the male of the species needs to keep up its strength as it can have more than 12 female partners in any one breeding system.
Male elephant seals keep a harem of up to 50 females.
The male gray seal tries to impress the ladies by stretching out his neck and showing off his nose.
Seals have been known to swim for as long as 8 months, and as far as 6,000 miles, without touching land.
Seal spend many months at a time at sea, so they must sleep in the water. Like other marine mammals, seals sleep in water with half of their brain awake so that they can detect and escape from predators. When they are asleep on land, both sides of their brain go into sleep.
Seals mainly inhabit polar and subpolar regions, particularly the North Atlantic, the North Pacific and the Southern Ocean. They are entirely absent from Indo-Malayan waters.
Seals usually require cool, nutrient-rich waters with temperatures lower than 20 °C (68 °F). Only monk seals live in waters that are not typically cool or rich in nutrients.
It remains a scientific mystery how Baikal Seals originally came to Lake Baikal, hundreds of kilometers from any ocean. Estimated to have inhabited Lake Baikal for some two million years, the Baikal Seal is the only true freshwater seal on Earth.
They have relatively long life expectancies – with some adults living for up to 30 years.
Humans used to hunt seals for their blubber, meat and fur, but they are now protected under international law.
The earless seals or true seals are found mainly in the cold seas of the world.
True seals include the grey seal whose main population is around British coast, and grows to 2.7 m 9 feet , also the shorter-nosed common seal found in coastal regions over much of the northern hemisphere.
ANATOMY
The largest seal is the Southern elephant seal which can be 6 metres (20 feet) long and weighs as much as four and a half tonnes.
The smallest of the species is the Baikal seal, which is only 1.2 m 4 feet long, and is the only seal to live in entirely in freshwater.
Streamlined in body shape, seals have thick blubber insulation, no external ear flaps and small front flippers.
The hind flippers point backwards and are swung from side to side to provide a thrust for swimming, but unlike the sea lion, they cannot be bought under the body for walking on them. To "walk" on land, a seal has to wriggle with their front flippers and abdominal muscles.
Deprived of sight and hearing, seals can still accurately pinpoint the locations of fish because they have 1,500 nerve endings in their whiskers.
Seal pups gain between three and five pounds each day because their mothers’ milk contains 50 per cent fat.
A seal was once abandoned in her colony because was ginger. Born with rare brownish-red fur and wonky blue eyes, the unfortunate baby seal was rescued from a beach on Tyuleniy Island, in the Caspian Sea, after it was abandoned by its mother. The pup's color is the result of an accumulation of iron in its fur.
BEHAVIOR
Seals are rampant carnivores – consuming up to five per cent of their body weight a day in fish, squid and scrustaceans.
Antarctic fur seals can eat about a ton of fish and krill a year – the male of the species needs to keep up its strength as it can have more than 12 female partners in any one breeding system.
Male elephant seals keep a harem of up to 50 females.
The male gray seal tries to impress the ladies by stretching out his neck and showing off his nose.
Seals have been known to swim for as long as 8 months, and as far as 6,000 miles, without touching land.
Seal spend many months at a time at sea, so they must sleep in the water. Like other marine mammals, seals sleep in water with half of their brain awake so that they can detect and escape from predators. When they are asleep on land, both sides of their brain go into sleep.
HABITAT
Seals mainly inhabit polar and subpolar regions, particularly the North Atlantic, the North Pacific and the Southern Ocean. They are entirely absent from Indo-Malayan waters.
Seals usually require cool, nutrient-rich waters with temperatures lower than 20 °C (68 °F). Only monk seals live in waters that are not typically cool or rich in nutrients.
It remains a scientific mystery how Baikal Seals originally came to Lake Baikal, hundreds of kilometers from any ocean. Estimated to have inhabited Lake Baikal for some two million years, the Baikal Seal is the only true freshwater seal on Earth.
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| Baikal Seal. Photo taken by Uryah |
They have relatively long life expectancies – with some adults living for up to 30 years.
Humans used to hunt seals for their blubber, meat and fur, but they are now protected under international law.
Northern elephant seals were hunted extensively for their oil and fur during the 19th century, leading to their populations declining significantly. In 1892 an expedition from the Smithsonian found what could have been the last eight individuals on Guadalupe Island of which the expedition killed several for their collection. The species has made a remarkable recovery since then. Conservation efforts, including protection under international agreements, have helped elephant seals to re-establish their populations and they are now considered to be a relatively abundant species.
Sources Hutchinson Encyclopedia, Daily Mail
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