Seals are marine mammals belonging to the family Phocidae, within the order Carnivora, and are inhabitants of almost all the world's seas Some of them have even colonized freshwater areas. They have a series of anatomical characteristics that allow them to survive in regions as cold as the poles, with very extreme temperatures and climatic conditions. Among them, we can name their large size, the thick layer of subcutaneous fat (under the skin), their fin-like limbs that allow them to be excellent swimmers when looking for food in the water, and their breast milk, which is very rich in calories. with which they feed their young. All this, added to other aspects, makes seals one of the most spectacular marine mammals that inhabit the seas. Of course, it is important to highlight that there are no types of seals with tusks, it is the walruses that present them and are part of another family.
If you want to know the types of seals that currently exist, don't miss this article on our site where we will tell you all about them.
Classification of seals
The great family Phocidae, within which the seals are found, is currently divided into two subfamilies with species that share anatomical, ecological and behavioral characteristics, but that differ in terms of their geographical distribution. As we mentioned, they are found in practically all the world's oceans and throughout evolution they have acquired different adaptations for marine life. On the one hand, we have the seals present in the northern hemisphere, and they are generally somewhat larger than their relatives, the southern hemisphere seals. Of the 19 species that exist, two of them are freshwater and the rest are marine, three of which live in warmer areas and not in icy waters.
They are classified into two subfamilies depending on their location. On the one hand, there is the subfamily Phocinae, which includes seals from the northern hemisphere, while the subfamily Monachinae includes species from the southern hemisphere and some species of the genus Monachus (monk seals).
Next, we will see in more detail some examples of each subfamily.
Seals of the subfamily Phocinae
The subfamily Phocinae is made up of a total of 10 types of seals. Here we highlight four:
Bearded Seal (Erignathus barbatus)
This species inhabits the Arctic Ocean and is medium in size, measuring about 2.2 meters although it can reach almost 3, and both the male and female are similar in size. The most striking characteristic of this species of seal is the position of its forelimbs, which are located frontally, unlike other species of seals, in addition, it has an abundant mustache, which is what gives it its name. Its body is brownish brown, being more reddish in the area of the head and neck. Another aspect that differentiates this species from the rest that make up this subfamily is the presence of a pair of nipples
It feeds on a wide variety of fish, clams and squid, which it hunts by diving. It does not generally venture to depths of more than 300 meters, unlike the young that can reach more than 400. The bearded seal is the favorite prey of polar bears, and has been hunted by the Inuit for centuries., inhabitants of the arctic regions.
Kingpot Seal (Cystophora cristata)
Also known as Helmet Seal, this species is found in the North Atlantic Ocean and the Arctic. Undoubtedly, what most characterizes this seal is the widening of the nasal cavities that the male has, which gave him the name of helmeted seal, since it gives him the appearance of having one on his head when he reaches adulthood, since it can be inflated with air.
Its size is around 3 meters in males, while females reach about 2 meters, which gives it sexual dimorphism. Its coloration is dark, with brown or black tones and the back is mottled. This species is not gregarious and only forms large groups during the mating season. In addition, females wean their young around the fourth or fifth day after birth, having one of the shortest lactation periods among mammals.
They are common in offshore areas, always on ocean ice from where they dive about 100 meters in search of food, which varies between a great diversity of fish and cephalopods.
Common or Spotted Seal (Phoca vitulina)
This is the most widely distributed type of seal, being found along the coastline along the North Atlantic and Pacific Oceans, in the North Sea and the B altic. It is medium-sized, the male reaching almost 2 meters; the female is somewhat smaller.
These seals are gray or cinnamon brown in color with a pattern of spots that varies from individual to individual, which characterizes this species. In addition, their nostrils are curved so that they look like a V. The common seal is gregarious and is always with its family members in rocky places where they rest and that, in addition, are well supplied with food, being very faithful to these places..
They have mechanoreceptors that allow them to identify objects that move under water, which offers them perfect orientation when hunting. They feed mainly on a wide variety of fish, although they can also consume crustaceans and hunt squid.
Striped Seal (Histriophoca fasciata)
This species is found in the arctic regions of the Pacific Ocean, in the Bering Sea and the Sea of Okhotsk and is the least known species of sealdue to their very remote habitats and because they spend a lot of time in the water. Its common name derives from the design of stripes or ribbons that cover its body, since adults have very distinctive markings on their fur, consisting of a dark background with a set of light bands that surround the head, the back of the body and the legs. front wings. In males, the background color can be dark brown or almost black and the bands almost white, while females show the same pattern, but with less contrast. Both male and female measure between 1.5 and 1.7 meters.
This species lives exclusively on ocean ice and during the breeding or moulting season, it looks for frozen platforms to carry out these processes. It has an air sac connected to the trachea, which when inflated provides buoyancy, which is often used to float and rest on the water. Like other species, the striped seal feeds on squid, shrimp and various fish.
Seals of the subfamily Monachinae
Within the subfamily Monachinae we find a total of nine types of seals, let's see the four most outstanding:
Crabeater Seal (Lobodon carcinophagus)
This species of seal is inhabitant of Antarctica, although there are also records of wandering individuals in New Zealand, Australia and South America. This species is more slender than other seals, can measure more than 2.5 meters and the color of its fur is dark greyish, becoming lighter in summer.
This is another species that depends exclusively on ocean ice packs, since it lives most of its life in them. In addition, its diet is based on more than 90% krill because, due to the structure of its teeth, it cannot capture other prey, acting as a filter. It is a social species that lives in small groups and where both sexes take care of the young. Likewise, it is one of the fastest seals, since they are capable of submerging more than 400 meters in 11 minutes.
Leopard seal (Hydrurga leptonyx)
The leopard seal is found in Antarctica and is also associated with ocean ice shelves. It is large in size, both females and males can reach more than three meters in length and its fur is gray, becoming lighter on the ventral part, with spots on the neck and chest, which gives it its name. Its appearance is muscular and its head resembles that of a large snake, with a very large mouth that reveals its long sharp teeth.
This is a solitary and aggressive species, being the main predator of the emperor penguin in Antarctica. In addition, their senses of sight and smell are highly developed, which makes them even more threatening. A wide variety of fish, squid, eggs of other birds and penguins enter their diet, since they can catch everything that enters their mouth.
Mediterranean monk seal (Monachus monachus)
The monk seal is distributed in the Mediterranean Sea and the North Atlantic Ocean, reaching the coasts of North Africa, although its distribution is becoming more limited, which makes it avery rare species to sight It inhabits coastal areas and beaches sheltered by cliffs with caves leading to the sea, where they generally breed. Its size is medium, it reaches about 2.8 meters in length, its body is elongated and its limbs are short but robust. Its fur is grayish brown and can be darker in the male.
Its current populations are very small, since it is a species that is in critical danger of extinction due to the loss of its habitat produced by humans, fishing overexploitation, diseases caused by red tides produced by algae, among other causes.
Northern Elephant Seal (Mirounga angustirostris)
This species is distributed throughout the Eastern Pacific Ocean, from Alaska to Baja California, where it inhabits oceanic islands. Its main characteristic is the large proboscis that the males have and which is used to roar, especially during the reproductive season when they compete between males. This is a large species, where the male can measure more than five meters in length and the female about three, so its sexual dimorphism is very marked. This is also associated with their reproductive mode, where the male can mate with dozens of females during the mating season.
They are nocturnal hunters and are capable of diving to more than 800 meters to search for food, which is based on fish, cephalopods, chimeras and small sharks.
Other types of seals
As we have mentioned, there are 19 species of seals that exist, therefore, below we name the remaining types of seal. Belonging to the subfamily Phocinae we find:
- Harpland Seal (Pagophilus groenlandica)
- Ringed Seal (Pusa hispida)
- Nerpa (Pusa siberica)
- Grey seal (Halichoerus grypus)
- Spotted seal (Phoca largha)
- Caspian Seal (Pusa caspica)
The missing seal species belonging to the Monachinae subfamily are:
- Hawaiian monk seal (Monachus schauinslandi)
- Caribbean monk seal (Monachus tropicalis)
- Southern Elephant Seal (Mirounga leonina)
- Ross Seal (Ommatophoca rossii)
- Weddell seal (Leptonychotes weddellii)
