Common sealPosted on July 25, 2018 - Last modified: August 5, 2018
common sealPhoca vitulina), they are a family of pinniped mammals adapted to living in a semi-aquatic environment. They are found in cold waters and there are more than 30 different species, the smallest seal being the Caspian seal and the largest the elephant seal. We can find other species such as the gray seal and the leopard seal that are known for their aggressive behavior.
More than 50 species of extinct seals have been described from fossils.
Table of Contents
The harbor seal can live up to 20 years of age, but it varies between species that live shorter and others that live up to 40 years. However, since they are appreciated as food by different predators, most seals will not grow old. The size varies between 1 m and 45 kg in weight for the Baikal seal, up to 5m and 3.200 kg for the southern elephant seal.
They present sexual dimorphism, that is, we can visually witness differences in shape, size, color, etc. between males and females. Their bodies are aerodynamic with four limbs turned into fins. In the water they are not as fast as dolphins but they are more agile and flexible.
Otarids use their front limbs to propel themselves through the water, while phocids and walruses use their hind legs. Otarids and walruses have limbs that can be placed below the body to be used on land and for fócids, locomotion on land is more uncomfortable. Otarids have visible outer ears, while phocids and walruses lack them. Pinnipeds have highly developed senses: their vision and hearing adapt to both air and water, and they have an advanced tactile system in their whiskers.
Certain species are well adapted to deep diving. To keep warm in the cold waters they have a layer of fat under their skin that insulates them. Except for the walrus, all species are covered in skin.
Seals emit a series of vocal sounds to communicate, notably the barking of California sea lions, the calls of walruses, and the complex songs of Weddell seals.
Pinnipeds are the most widespread and common, but the vast majority of species prefer the cold waters of the northern and southern hemisphere. Most of their lives are spent in the water, but they will reach the shoreline to mate, reproduce, molt, or escape from its many predators.
The seals are carnivorous animals and they feed mainly on fish and marine invertebrates such as shrimp and crabs, but certain species, such as the leopard seal, eat large vertebrates such as penguins and other seals.
The seal is a frequent and simple prey for many predators. They are hunted both on land and in water, due to their medium size and peaceful nature. Predators include polar bears, sharks, and even humans, usually Arctic people, who hunt them for their oil, meat, and skin.
Male pinniped seals practice polygamy, although the level varies by species. Males that mate on land will mate with larger numbers of females than species that breed in water or ice.
The cubs will be born during the spring and summer months where temperatures are warmer and food is plentiful, with the females taking full responsibility for raising them. The mothers of some species fast and feed their young for a very short period of time, while other species search for food in the sea by making several trips during the lactation period. Blackberries nurse their young while at sea.
After mating, gestation lasts about 12 months and they are born on land. Young develop rapidly and in certain species can swim within hours of being born.
State of conservation
Humans have obtained certain products from seals such as meat, blubber and fur coats, especially the indigenous peoples of the Arctic. They have also been represented in cultures around the world.
Due to the indiscriminate hunting of certain industries, various species of seals such as the Japanese marine and the Caribbean monk seal have become extinct. And the Mediterranean monk seal and the Hawaiian monk seal are currently in danger of extinction by the International Union for Conservation of Nature.
In addition to hunting, they are also threatened by accidents (cars with boats), marine pollution and conflicts with the local population. But today, seals and walruses are protected under international law.