Sea lions are one of the largest marine mammals that double up as amphibians, i.e., they are equally capable on land as they are under water. These beautiful (though less than graceful) sea creatures are fast disappearing from earth, causes of which are still under study. Their inexplicable disappearance has made conversationalists work overtime to find ways to increase their numbers and get them off the endangered animals list.
They may be bulky and overweight, less flattering and attractive, and relatively unknown to the masses, but they form an essential link in the food chain of our ecosystem.
Territory and Location
The population of these creatures can be divided in two parts: the Eastern population (California, British Columbia, and South Eastern Alaska) and the Western population (Gulf of Alaska, Bering Sea, Russia, and Japan). Their territories range far and wide in both the hemispheres and in all waters except the Atlantic ocean.
They are commonly known as the 'Stellar sea lions', and are scientifically known as Eumetopias jubatus. They form a part of the Otaridae family, which is a collective grouping of what are known as 'eared seals'. The genus includes any of their 7 species listed under the group of 'modern pinnipeds'. Pinnipeds are mammals with external ear flaps and long front flippers. They are amphibious and are at equal ease both in the water and on land. Some awesome facts about them are that they can dive to the depths of around 1000 feet despite their bulk. They can also hold their breath under water for 10 to 20 minutes, as they have the ability to slow their heart rates whenever needed. They can swim at a speed of about 11 to 24 meters an hour and gallop on land at 25 to 30 kilometers per hour.
They are oddly designed. They look rather inelegant walking on land on their four flippers. Their bodies are, however, perfectly streamlined for movement in dense waters. They have a short, coarse fur coat that looks yellowish-brown when dry. The males and females weigh 907 kg (2000 lbs) and 272 kg (600 lbs) respectively, on an average. These marine mammals can grow to about 7 to 10 feet in length. Under zoological conditions, their life spans extend to 20 - 30 years, but in the wild, they only survive to about 10 or 15 years.
The main diet of these lions consists of various fish and cephalopods. These opportunistic predators will feed on anything convenient. They prey on squid, octopus, fish, seals, sharks, and pups of other mammals. Their diet varies according to the geographical region as well as seasonal change. They are voracious eaters, and sometimes, they even eat their own kids.
Social Life and Reproduction Cycles
Every year in spring, these animals gather in large numbers at their breeding sites, also known as rookeries. Here, the females (which arrive later than the males) are herded into male territory by pre-appointed sea lions. Harems of about 15 or more females are thus formed, and it is here that they give birth to one offspring (that was conceived during the last cycle). Mating begins soon after the birth of a pup, as conception for the next year's cycle starts. Gestation period lasts up to 10 to 11 months. Females produce just one pup each year and start reproducing at 4 - 6 years of age.
Pups remain with their mothers for about a year, after which the 'yearlings' form playgroups for mock battles and play. The pups are initially black in color, but molt their coats to light brown ones by the end of their second year. Male pups mature between 3 to 8 years but are unable to hold territory until they are 10 years old. While the others return to the rookeries each year, male pups do not return until they are 2 years old. Even then, these bachelors are isolated till they are large enough to compete for their territories. The male species are polygamous.
Sea lion rookeries are specially chosen congregation places. They are chosen, taking into account certain factors, like food proximity, predator protection, topography, surf conditions, etc. Their rookeries are normally unhygienic and stinky, as females rarely go underwater for defecation. Infestation by parasites could be a reason for high pup mortality.
The biggest threat for this species is reduction in their habitat. Their natural foods are also on a decline. Japan, for example, has given permission for killing a whooping 116 of these lions per year, as they are a threat to commercial fisheries. Their natural predators - killer whales, sharks, polar bears, coyotes, and wolves, are also responsible for a fall in their numbers. A major chunk of the blame though, goes to man. Plastic pollution, oil spills, fishing nets, etc are more of a threat to them, than what we'd even like to consider. Apart from these, there is always disease and environmental change.
If nothing is done soon, our children might never know about them. They will fade away in time like the dodo and the already extinct Japanese sea lion. We can wake up now while there is still time. A first thing anyone who cares can do, is to do away with the fur accessories, meat, and oils of this animal. Isn't it a small price to pay to save a whole breed of these giants?