Description:
The sea otter (Enydra lutirs) is highly adaptable to cold waters. Its fur has nearly one million hairs per square inch, making it the thickest and densest of any other animal. They have long water-resistant hairs and short underfur, which keeps them warm and dry. Since an otter’s fur has to be clean and immaculate at all times for the fur to remain warm and waterproof, it is no wonder that these small sea mammals spend most of their time grooming themselves. They are extremely flexible and able to reach every part of their body for grooming. Their fur can be anywhere from a yellow brown to almost black, but it is usually a darker shade of brown with gray specks. Mature sea otters also exhibit lighter fur coloration along the chest, throat and head. Sea otters are quite adaptable in various other ways including: their front paws come inner padding and retractable claws for catching and grasping their prey, they can close their ears and nostrils, and their long hind-feet are webbed and flat to enable ultimate propulsion during swimming. Sea otters are capable of swimming at about 5.6 mph. Sea otters are among the smallest sea mammals; a full-grown male is about 49-99 lbs in weight and usually 4-5 ft in length. The females are slightly smaller at an average weight between 30-73 lbs and a length of 3.3-4.7 ft. Sea otters will rest in rafts of the same sex made up of usually 10-100 otters. The largest raft size ever recorded was over 2000 otters! They mainly reside in the northern and eastern North Pacific Ocean.
Diet:
Sea otters use their long, sensitive whiskers and front paws to find their prey if they’re vision is limited by dark or murky water. They usually forage alone 2-3 times a day (before sun-rise, afternoon and sometimes around midnight). An otter will spend on average 24-60% of its time foraging for food, varying upon how easily and quickly the food is attained. They keep whatever food they collect by directly catching, overturning boulders, digging, and removing creatures from kelp in pouches under both legs, which extend to the chest area. Later, they will lie on their backs on the surface to consume its findings. Unlike many other mammals the sea otter can use tools such as rocks to release abalones in order for consumption. To make up for all the heat energy they lose from living in cold waters, sea otters have to eat 25-38% of their total body weight on a daily basis. They have 32 flat round teeth, which are used for crushing their prey, which consists of over 100 different species. They tend to favor marine invertebrates like mollusks, clams, mussels, snails, sea urchins, octopus, limpets crabs and abalones, Although, most of an otter’s needed water is attained through their meals, their large kidneys make consuming sea water directly to avoid dehydration.
Mating:
Sea otters have multiple partners, making them polygamous. Mating between otters can be very rough, to the point where the female will usually have scars on their nose from the male biting her and holding her head under water in some cases. Female otters are able to delay their egg from implanting in their uterus for up to 8 months, making the gestation period anywhere from 4-12 months. Pregnancy only last for 4 months. Sea otters usually breed every or every other year, depending on where they live. Otters, which inhabit the coast of California normally breed every year, while otters that live on the coast of Alaska tend to breed every other year. Females will give birth to one pup with an average weight between 3-5 lbs.The chance of twins occurring in 1 in 50 births. Unfortunately, in most cases only one pup will survive. Infant mortality is about 75%, meaning only 1 in 4 pups survive their first year on average. Once the pup is born, the mother will spend hours and hours grooming its fur to the point where the pup will not be able to dive underwater. 13 weeks after birth, the baby fur will be replaced by adult fur. Nursing can last anywhere from 4-12 months. Usually around 4 months, pups will begin to learn how to dive underwater and retrieve. They usually only surface with pebbles.
Threats and Predators:
In 1808 commercial hunting was put to a stop by the Russian-American company in hopes of saving the species from extinction. But, in 1867, after the Russian population grew to over 100,000 American began to hunt them excessively again, endangering their population once more. As their numbers depleted, their furs became more expensive, putting the otters in even more demand. Finally in the 1911, Japan, Russia, Great Britain and the United States made the Treaty for the Preservation and Protection of Fur Seals. Although, this species has made a remarkable rebound they are still considered endangered by the IUCN. Primarily, sea otters are threatened by oil pollution, fishing accidents, poaching. Among those, oil spills are most serious because when an otter’s fur becomes coated with oil, it can no longer hold air that enables them to keep warm. This will usually result in death by hypothermia. If they do survive, their kidneys, liver and lungs become damaged from oil ingestion. Sea lions, bald eagles and orcas prey upon sea otters, especially the pups. There has also been reports of great white sharks being responsible for 10% of all otter deaths and one of main reasons sea otters aren’t inhabiting further north.
References:
http://animals.nationalgeographic.com/animals/mammals/sea-otter.html
