EARED SEAL

EARED SEAL

When you look at seals they look all the same at first glance. However, if you look closer there are two different groups. One of the groups has retained a distinct, protruding ears hence the name 'Eared Seals' the other group has not.

Of course, all seals have ears but ears of the so called true seal are reduced to small openings which, it is assumed, make them more streamlined.

This minor point comes from a complete separate evolution. The true seal is thought to have evolved from otter-like creatures in the North Atlantic, about 15 million years ago. The eared seal evolved from dog-like creatures in the North Pacific about 25 million years ago. From this evolution they have a dog-like look, a very great mobility on land which in comparison the true seals is almost helpless on land.

TRUE SEAL COLONY

On land the true seal lies on its stomach with the front flippers stretch out on either side. The hind flippers trailing on the ground and to move forward it humps its body along.

On the other hand the eared seal stands on all four of its limbs. The front flippers are equipped with powerful muscles that bear the animal's weight. The hind limbs are turned forward under the body instead of trailing behind. When it moves slowly it waddles on the heels. The tips of the flippers are held upward from the ground. When it feels danger, it speeds up and throws both front flippers forward - like a man on crutches.  It looks clumsy but it can move fast and outrun a man.

Again the swimming techniques are quite different. The true seal uses its hind flippers and with powerful strokes propels itself through the water. The eared seal zooms through the water with using his front flippers and the hind flippers are only used like rudders. Therefore, all the muscle-power comes from the shoulder and neck. Through these exercises it keeps the muscles strong to use them on land.

Like all seals it spends its life in water and through evolution it became an efficient swimmer. The streamlined body gives an effortless efficiency in water. In spite of the sleek body of the seal it has a small face preventing heat loss. The thick fat layer under the skin gives not only insulation but also a further streamlining.

ANTARCTIC FUR SEAL

The fur seal has a tense woolly undercoat with longer and coarser guard hair on top for further protection 
he two types of hairs couple and is extremely protective against water reaches the skin, preventing heat loss.

However, during a deep sea dive the insulation of the fur become less because the warm in the fur will be compressed by water pressure. Despite of this the Cape fur seal dives often to a depth of up to 100m. Californian sea lion have been trained to dive even deeper. The eared seal are not such great diver. The reason is that they can't or won't hold their breath for long periods. The true seal can stay under water for 20 minutes. It empties its lungs stores the high concentrated oxygen in its blood. Eared seal do not have this capability and only stay under water for about five minutes.

When on land the fur seal is very clumsy but in water it is like a torpedo and with intelligence plus resourcefulness of a wolf. They are predators but some are better than others. in the group of eared seals, the fur seal feeds almost entirely on krill. These shrimp-like creatures are in their millions in the Polar seas. They are the diet of the great whale but them almost extinct in the Southern Ocean and it is thought that this may have resulted of a population explosion of the Arctic fur seal.

On a whole fur seal and sea lions kill and eat anything they get hold of. They live in a region of whirling ocean currents bringing up nutrient-rich water from the seabed near the coast. These nutrients then nourish the microscopic algae floating in the sun on the surface of the water. This will provide food for the tiny floating animals. Great shoals of fish will be attracted which then feed the seals.

Eared seal hunts in the middle of the water and on seabeds. It feeds on fish, squid and sometimes on penguins. as well as crabs and crayfish which are at the bottom of the sea.

On the beach it can see fairly well in bright sunshine but not much when the light is fading.  In the sea it can see everything in sharp focus even when the light is almost zero. The seal doesn't depend on eyesight. It had been noticed that a totally blind eared seal is well fed in the wild. It proves that other senses are used to find food.

The ears are developed to cope with the greater pressure of sound waves in water. It also is capable to take the increasing pressure as it dives, through a special mechanism. The hearing is remarkable in pinpointing the sounds of its prey and it can home in on it in dark, cloudy water.

Through its cat-like whiskers it picks up vibration in the water. Each whisker has a complex network of nerve fibres which sends messages to the brain. This gives it the ability to track its prey in total darkness.

The fur seal and sea lions breed in tightly packed colonies and give birth. They rear their babies and mate again before they return to the sea at the end of the season. They developed this colonial habit because of the shortage of beaches. The other reason is that they are vulnerable to predators.  Although the eared seal is quite mobile it still gathers together into groups and the female comes to the beach to give birth.

They mate soon after the female gave birth. The male arrives at their breeding ground first. When the female emerges out of the water it has to move into his territory. This gives the male an opportunity to have a harem of up to 50 females. It leaves a lot of other males or bulls without any female. There is a lot of fighting going on and some are so serious insured, it leads to death even with their thick hide.

SEA LION AND HIS HAREM

When a bull claimed a territory he has to stay there right through the mating season and live on his fat reserves. If he doesn't, he looses his place. The females arrive two to three weeks after the bulls claimed his place. The pregnant females first. The seals have delayed development of the foetus. This enables the female to give birth exactly one year later. The female stays with its pup for six days then she wanders about and goes back to sea. The male will mate with her when she starts to wander around. She goes to sea hunting and returns to the pups to suckle them for at least 100 days.

SEAL PUP

A number of species suckle their pups for a year and when she returns to the beach to give birth; it is not unusually she is accompanied by her year old pup.

The secluded breeding beaches provide protection from predators but not from man. When they discovered in 1786 the huge colonies of northern fur seals on the Alaskan Pribil of Islands; the sealers wiped them out. The same happened on South Georgia with the Antarctic fur seals in the 19th century.

It was their skin with their beautiful woolly undercoat which the sealers were after and they didn't do a great selection amongst the animals. They slaughtered any seal that came on land, including pregnant females. It wasn't surprisingly that by 1910 the Antarctic fur seal was practically extinct and the other species were not far off.

It was just in time when the hunting restriction came into power during the early 20th century otherwise the seals would have disappeared. Only through sheer conservation the population has increased, especially the Antarctic fur seal. Due to this timely intervention the eared seals are thriving again. However, the large mammals round the world do not do so well.

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