There are several species of seals living in both the North and the South Poles, and they all have something in common: They are perfectly adapted to live in environments with extremely low temperatures.
It is interesting to see how these beautiful mammals have adapted to their environment by evolving particular physical characteristics. Other less prepared animals could not cope with the cold temperature of the water and the land.
Do you want to learn more about seals? Stay with us at AnimalWised and learn all about the different types of seals around the world and how each species has adapted to its habitat. Read on!
Pinnipeds: A varied group
Pinnipeds are a clade, that is, a branch of species. This branch in particular consists of three distinct families, but all their members are commonly known as "seals". These families include:
- Otariids: Eared seals. They are distinguished by having pinnae - that is, small ear flaps - and forward-facing hind flippers that allow them to get across land better than other kinds of seals. This family mainly consists of the so-called sea lions and fur seals, and they inhabit the subpolar and temperate regions of the two hemispheres, but not the north Atlantic Ocean.
- Phocids: True or earless seals. They lack pinnae and their hind flippers face backwards. There are about 20 species of seals, and they inhabit polar to temperate regions of the two hemispheres.
- Odobenids: There is only one living member in this family, the walrus, which only lives in the Arctic Ocean.
How are seals adapted to cold waters?
Most types of seals are perfectly adapted to the icy polar waters, as they have developed a thick layer of fat called "blubber" that covers their body. Apart from keeping them warm, this layer gives seals great buoyancy, which allows them to show an extraordinary agility in the sea that they don't have on the ground, where they are clumsy. Seals get this layer of fat by consuming around 5 kg of fish and cephalopods per day, although the exact volume of the intake depends on the species.
Overfishing is causing the decimation of the number of sharks - a natural predator to the seal - which in turn causes a dangerous increase of the seal population in some regions. This is the case of the California sea lion. Having excessive numbers of individuals within a species is as dangerous as having too little. Too many causes famine, disease and species degeneration. The scientific community has already raised concern about this serious problem.
However, some types of seals are in serious danger of disappearing. Three are vulnerable, four are endangered and two are critically endangered; they are victims of climate change, as the ice they live on is disappearing. Their hunt is regulated, and in some cases totally forbidden.
Arctic seals
Several species of seal live in the polar and subpolar regions of the Arctic Ocean:
- The northern fur seal (Callorhinus ursinus) is an eared seal. It lives in the north Pacific Ocean, the Bering Sea and the Sea of Okhotsk. Male northern fur seals are much larger than females. They live in colonies sited on rocky shorelines. They have dark skin, small heads and a peculiar curved mouth. This is a vulnerable species.
- The harp or saddleback seal (Pagophilus groenlandicus) lives on the Arctic, around Greenland. The color of this true seal's fur is a very light silver, almost white, although they have some irregular dark patches on their back.
- The gray, Atlantic or horsehead seal (Halichoerus grypus) are one of the best-known types of seals, as they are found in the majority of zoos. Males, who can reach 3.3 m (10.8 ft) long, are double the size of females. This species' population is growing. Their coloring can range from brown to very dark grey. It is one of the most ravenous species when it comes to food. They are true seals, and they inhabit the shores of the North Atlantic Ocean.
Antarctic seals
Some species of seals that live in Antarctica also live in the Arctic, but others are only found in the Southern Hemisphere.
- The leopard seal or sea leopard (Hydrurga leptonyx) is one of the largest types of seals, as they are about 3.5 m (11.5 ft) long. This true seal is a very aggressive animal, and it can attack humans. It feeds on penguins, fish and other seals. This species only inhabits Antarctica and the southern polar circle, and their only predators are orcas. Few studies have been conducted on them as they are dangerous to approach.
- The Antarctic fur seal (Arctocephalus gazella) is a type of eared seal that was close to extinction in the nineteenth century, but now there are more than 4,000,000 individuals and counting. They are slimmer than other species of seals. They are found close to Antarctica.
- The southern elephant seal (Mirounga leonina) is the largest and heaviest seal - and the largest carnivore as well! Males are double the length of females and four times heavier; they can reach up to 6 m (19 ft) in length and 4000 kg (8800 lb) in weight. They are called "elephants" due to their huge size and the type of short trunk that males have on their face. Their favorite habitat is rocky southern coastlines.
General morphology of seals
Even the smallest types of seals are generally large animals. This makes them strong, and they don't have as many predators as other species because they are fast and tough.
Their fusiform bodies, and the thick layer of fat that protects them from the cold and provides buoyancy, makes them extraordinary swimmers. In addition, they can hold their breath underwater for several minutes, allowing them to relentlessly hunt the fish which they need to live.
Image from National Geographic
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