Seals are very fascinating semi-aquatic, marine mammals that have a lot more than just lying all day long on the land in search of food. There are about 33 different species of seals which are distributed around the globe and around 50 species are thought to be extinct. Also known as Pinnipeds, seal live in extremely cold environment and do so without any difficulty. They are carnivores in nature and are closely associated with bears and musteloids. While it is practically impossible to cover every aspect about seal in this article, few very important and interesting facts about seals are as follows.
There are two families of seals, Otariidae which are the eared seals including fur seals and sea lions and the second family, Phocidae, belongs to earless seals also called true seals. They include the common seals and harbor. Seals have finned foot or wing foot hence given the name pinnipeds (Pinnipedia means winged foot in Latin).
Seals can stay under water for straight 30 minutes before coming to the surface for taking up air. This is because of a high concentration of hemoglobin in their blood; a substance that carries oxygen. Different species have been found to dive to various depths. Most can dive under water for up to 1000 feet deep while there are few which can go as down as 3000 feet. It is believed that they can go deeper than this in their quest for food.
The extremely cold weather has no evident effect on seals as it does on other mammals. These creatures have a thick layer of blubber underneath their skin which acts as an insulating layer of fat, keeping the cold away. Their body temperature is hence well regulated owing to this as well as being warm blooded.
From the 33 species of seals, 20 carry out their breeding process on land while the remaining 13 prefer ice. Those breeding on land are usually polygynous, where a group of females gather together and are mated by few male seals. Only a single pup is born and summer or spring are the desired months of giving birth.
The milk provided to the pup by the mother seal contains up to 60% fat which allows the pup to grow at an exceptionally fast rate. 3 to 5 pounds are gained by the pups each day. Some pups also tend to drink the milk from other parenting seals and grow much faster, a concept known as alloparenting. Male pinnipeds have no defined role in nursing their young ones. They might help their pups swim though.
Communication between seals occurs via a number of vocalization both on land and under water. These include rasps, growls, rattles, chirps, clicks and whistles. Females have high frequency vocals as compared to males. In few species, male seals are able to produce gong-like calls to attract female seals. Musical notes are also produced by few through their inflated throats.
Seals are not very versatile when it comes to their diets. Most preferred and readily available diet includes fish and squid. Seals make use of their whiskers to detect the prey around. The vibrations made by the prey are detected by the seal’s whiskers and the follows the hunt.
Seals have different sleep patterns on land and in water. On land, a seal is completely asleep with both hemispheres of the brain in the sleep mode. On the other hand, under water, a seal is never fully asleep. It sleeps with half part of its brain still awake. This is a defense mechanism against the predators and to keep an eye on their moves.
Hundreds or even thousands of seals are slaughtered in Canada every year without a rational reason. The issue has turned into a political debate involving a number of countries.
The milk that is produced by the female seals is normally around 50% fat that leads to an astonishing growth. The baby seals are capable of gaining around 3-5 pounds on daily basis.