The pinniped family is made up of walruses seals and sea lions. Common attributes shared by these organisms.
The Pinniped family is an order of marine carnivores that includes 20 genera and 31 species of seal, sea lion, and walrus. Despite the obvious differences in these animals, they also share some major common characteristics. Pinnipeds have long torpedo-shaped, streamlined bodies which allow them to cut through the water. The four legs of a pinniped are modified into flippers, making them ideal for a life mostly spent in the water. What would equate to the upper arm and upper leg in another animal are actually enclosed inside the pinnipeds body, allowing only the "wrist" and "hand" or "ankle" and "foot" to protrude. Its "hands" and "feet" are elongated and flattened. While having 5 digits like many other animals (including us) they are held together by webs of skin, which form excellent oarlike devices for propelling them through the water.
In addition to these characteristics, pinnipeds have many other advantages that fit them for a life spent in a cold, watery, world. In accordance with their streamlined shape, their external ears are either very small or non-existent. Their nostrils consist of 2 slits, which, along with their ears, can be closed when they are underwater. Their skin is coated with a combination of coarse and fine hairs. The fine hairs are short and slick and provide warmth and insulation against the elements. The coarse hair act as protectors for the fine hairs, helping to reduce wear and tear. Under the skin of the pinniped is a thick layer of oily fat, or blubber, which not only provides insulation but is also a source of energy for the animal. Another way they protect themselves from the icy water is found in the bllod vessels of their skin. Pinnipeds have the ability to contract the small arterioles, or blood vessels, in the skin allowing less heat to escape through the skin. All of these characteristics help to maintain their body temperature at a constant 95 degrees even in the iciest water.
A pinnipeds weight varies greatly from species to species, as much as 200 lbs to several tons, with the males generally being larger than the females. Their teeth vary, but are usually extremely small, bearing the name post canines or cheek teeth. It is possible to determine the age of a pinniped by examining a cross section of their teeth. Once the tooth emerges from the gum, the root continues to grow, forming a dentine ring around it for each year the animal lives. Similar to counting the rings on a tree, a pinnipeds age can be determined by counting the rings around the root of an extracted root.
Though clumsy on land, the pinniped is exceedingly graceful in the water. They propel their bodies through the water by moving their flexible bodies and their flippers. In the Otariidae and Odobenidae families get their power from their front limbs, while the Phocidae family get most of their swimming power from the rear flippers. Most pinnipeds are carnivorous, migrating to find enough to eat. Some spend much of their time on land and others reside primarily in the sea. Either way, the pinniped is a unusual mammal, whose habits and characteristic continue to fascinate people the world over.
