Steller sea lion, also known as the northern sea lion, is a type of sea lion native to northern Pacific. This sea lion is the only residing member of the genus Eumetopias. It is the largest of all the other eared seals. This particular species of mammal is the largest species of the ottarids and the fourth largest species of the pinnipeds. Stellers are the largest of all the existing sea lions and are sometime confused with California sea lions.
Table of Contents
Scientific Classification
Animalia
Chordata
Mammalia
Carnivora
Otariidae
Eumetopias
Eumetopias Jubatus
Table Of Content
Table of Contents
Scientific Classification
Animalia
Chordata
Mammalia
Carnivora
Otariidae
Eumetopias
Eumetopias Jubatus
Table of Contents
Steller sea lions mainly scavenge near the sea shores and aquatic waters. They are well known for their physical appearance and behavioral characteristics. The species is named after the great naturalist Georg Wilhelm Steller, who was the first one to describe them in the year 1741.
Steller Sea Lion
Physical Description
Length: Average length of this species range within 8.2 ft.
Weight: These sea lions have an average weight of 260 kg
BodyColor: Adult ones are of light yellowish and reddish color.
Fur: They have strong coat of fur that molts every year. Both sexes have long white color whiskers on their muzzle.
Flippers: Their flippers are black in color and are longer than the hind flippers. Their flippers are the chief means of motive power in water.
Habitat
Steller Sea lions inhabit cool coastal waters. When not in the water, they prefer gathering on breeding grounds and haulouts which are known to be isolated rocky island. They prefer terrestrial habitats so that they can rest, molt and mate. They are often seen in the beaches as well as in the sea. Sea lions can live in water for a long period of time. During mating season, sea lions migrate south.
Distribution
Their distribution range is quite wide. Their range begins from the Kuril Island to the Gulf of Alaska via the sea of Okhotsk in Russia. They are also found in the south to Ano Nuevo Island off central California. Basically they bred at the Channel Islands but recent evidences suggest that their population is declining. Their population is divided into an eastern and western stock through the middle of Gulf of Alaska.
Behavior
They have many interesting behavioral characteristics:
Steller Sea lions are aggressive in nature
Male sea lions dip their heads up and down when singing
They are frequently seen gathering in rookeries
Sea lions can travel long distances to find food
They can dive up to a depth of 600 feet or less. Their diving duration is not more than 2mins
They enter estuarine environments and feed on some fresh water fish like sturgeon
Diet
Though they forage to survive but it is the quality of prey that determines how much they have to eat. Their diet chart is composed of walleye Pollock, Atka mackerel, halibut, flatfish, pacific cod, rock fish, sculpins and cephalopods. They prefer schooling fish and prefer staying between intertidal zones and continental shelves. Occasionally they prey on northern fur seals, harbor seals, and sea otter pups.
Steller Sea Lion Photo
Adaptation
They do have some well-adaptive features:
They are equipped with forelimbs that provide the bulk of their forward propulsion
Their hind flippers supports them with steering
Their neck muscle allows greater range of movement in the head and neck
They swim fast and this is one of the useful adaptations for their predatory lifestyle
Rearing their pups on land helps these mammals reduce predation upon their young
Predators
Steller Sea lions are often attacked by predators such as transient killer whales and great white sharks. They are the intense predators themselves and feed on variety of fishes such as rockfish, capelin, and flatfish.
Mating Season
Their mating season is between the end of May and beginning of June. During this time the female sea lions returns to her home rookery. Rookery refers to an isolated rock where adults gather for mating and breeding.
Baby Steller Sea Lion
Mating
During their breeding season, male sea lions establish as well as defend individual territories on the rookeries. After a week, female lions arrive, accompanied by immature offspring organizing fluid collections throughout the rookery. Steller sea lions are polygynous and like the other species; they do not pressurize individual females into serails but manage the spacial territories among which the females can move freely. Sea lions mainly use three types of territories- aquatic, semi-aquatic and terrestrial.
Pregnant sea lions give birth after reaching the rookery and intercourse begins 1-2 weeks after giving birth. Until and unless the fall starts, the fertilized egg will not become embedded in the wall of the uterus. The boundaries of the territories are distinct by several natural features that include rocks, faults in rocks and much more. Territories remain steady for only 60 days.
Life cycle
Pregnant female give birth soon after reaching rookery. After a week of nursing female sea lions begin taking longer foraging tips leaving the pups behind. It is at the end of summer that the mother and the pup leave the territory. Pups remain with their mother for as long as four years. Mother sea lions are rarely seen feeding their daughters because the pups are quick learners, and start feeding themselves quite fast.
Life Span
Their average life span for males is 20 – 23 years, while females have been documented to live up to 30 years.
Conservation Status
IUCN has listed this species in the “endangered” category. Their population is declining and the suspected cause behind the decline is over-fishing.
Interesting Facts
There are many fun facts to know about this species of mammal:
At around 3-7 years, Steller Sea lions become sexually mature.
Both mating as well as giving birth takes place on land.
The duration of pregnancy is 11 1/2 months.
They can travel up to 250 miles in search of food.
