Pinnipeds are a small group of approximately 30 species. There are three families:
- real seals;
- eared seals;
- walruses.
Predatory animals live mainly in water. On land stay in certain life periods.
General characteristics
As already mentioned, representatives of this group are walruses and seals. We describe their general characteristics. Pinniped mammals are rather large animals with a maximum body weight of 3.5 tons and a trunk length of up to 6 meters. The elongated rounded body tapers towards the head and tail. The neck is thick sedentary, with the exception of eared seals. Most of the limbs are hidden in the trunk bag. A thick leathery membrane connects the fingers of the limbs, forming fins. All this is characteristic of these mammals (pinnipeds). In different species of animals, the claws are not equally developed.
They use their limbs only for movement. With the help of the rear fins, animals make oscillatory movements. In this case, the main muscle load falls on the back of the body. The front flippers balance the huge torso and act as a helm. The listed signs of pinnipeds indicate their adaptation to the aquatic environment.
The skin is thick with hard coat. The subcutaneous fat layer reliably protects against hypothermia. The teeth of this class of animals are intended only for holding and grasping food. The brain box is large, the brain is large. There are no external shells, but their hearing is good. When immersed in the water surface, the auditory opening narrows, thanks to the muscles. Pinnipeds can make faint sounds. The organs of smell are developed satisfactorily. Vision is practically absent. Vibrissas, which are long hairs, serve as the main organ of touch of animals.
Extruding forage, pinnipeds are able to stay in water for a long time. The size of the lungs is larger than that of terrestrial predators, and provide a complete exhalation and breath of a new portion of air. Lung tissue is elastic, thickened pleura, developed muscles.
Pinnipeds feed on crustaceans, mollusks, seabirds, and fish. Food is obtained only in the depths of the waters.
Walruses and seals prefer to rest on ice floes. Pinnipeds lead a herd lifestyle. The largest accumulations of animals are formed during the onset of breeding and molting. Some prefer a sedentary lifestyle, others migrate.
Natural enemies are:
- sea leopards;
- White bears;
- large sharks;
- killer whales.
Pinniped mammals go ashore or ice to mate and reproduce. At three years of age, puberty begins. Mostly one cub is born once a year. The body of the newborn is covered with thick fur, which differs in color and structure from the fur of adults. After a few weeks, the fur of the young generation is changing. Children grow up quickly, eating mother’s fat milk. After feeding, the cub becomes independent. Pinnipeds live up to 40 years.
Walruses
Walrus is one of the largest mammals in the class of pinnipeds.
Representatives of this class can be found in the Chukchi Sea, near the Franz Josef Land archipelago, off the coast of Novaya Zemlya islands, in the shallow seas of the Arctic Ocean.
Description
Walruses have powerful tusks of 2–4 kg each, which protrude 50 cm above the gum. In females, they are thinner and shorter. The main function of the tusks is to obtain food by loosening the sandy or silty bottom surface. Walruses in length can reach up to 4 m, and weigh 1.5 tons. Despite this body weight, they are motile and agile animals. The whole body of mammals is covered with hard and rare reddish-colored hairs. Subcutaneous fat up to 10 cm thick reliably protects against hypothermia.
Walruses do not freeze in ice water and they are not afraid of sharp frosts. Due to the presence of a subcutaneous air sac, which is connected to the pharynx, they do not drown in water during sound sleep. On the upper lip there are thick, mobile and thick, located in several rows vibrissa (sensory organs). By smell they learn about the approach of danger. They have poor eyesight. External auricles absent. The nostrils and ear holes close tightly when immersed in water. Flippers help animals dive and swim. The back flippers help push off from the surface of the earth and ice.
Lifestyle
On ice floes or on coastlines, rookeries are arranged. In case of danger, they panic, rise from their homes and, crushing each other, go into the water, leaving behind them the carcasses of dead animals.
Breeding
Walruses breed from the age of five years once every three or four years. Walruses have one cub. The female feeds him until fangs (tusks) grow. She is a very caring mother and will never leave her cub in danger.
Threats
An uncontrolled fishing of walruses led to a significant decrease in numbers. Since the fifties of the last century, a ban has been established on their hunt. An exception was made only for the local population (Yakuts, Chukchi), who are licensed to hunt walruses in order to satisfy their personal needs. Some species of walruses are included in the Red Book as endangered mammals.
