Sea Otters

Sea otters may look cute and furry from the outside but they have many attributes that help them to survive in their natural habitat. Along with being one of the smartest mammals, they also have finely tuned senses that help protect them and help them hunt. Their cute and furry appearance is not deception, despite living in the wild, they are very social and often swim along side boats and scuba divers.

This became very dangerous when poachers realized the value of their pelts, and sea otters were hunted to near extinction The sea otter is found in the weasel family. It lives along the coast of the Pacific Ocean in North America and Asia. Their habitats range from the Russia to California. Their habitat is made of the sea floor where they catch food and the sea surface where they eat, groom, rest and socialize. They prefer shallow water that is less than 130 feet because it allows them to get food easier. However they can dive up to 400 feet if they need to.

The water temperatures in these areas range from 21 degrees C to 38 degrees C below their core body temperature of 39 degrees C. They will frequently live in areas, which have kelp beds. They will raft in the kelp bed canopies. They use the seaweed in the beds to anchor themselves so that they do not float away. Mothers also tend to leave their pups in kelp beds to go hunt for food. All otters have the ability to produce sound and communicate vocally. However giant otters communicate more than other otters and they are also louder. Scientists have discerned about nine different sounds including some for anger, warning, and affection. A Cape clawless otter produces powerful, high-pitched shrieks when disturbed or when trying to attract attention.

The Asian small-clawed otter has a repertoire of at least 12 different vocalizations. Scent is the most important sense for communication in all freshwater species. River otters have scent glands at the base of the tail. They deposit their musky scent on their spraint. Spraint stations tend to be evenly spaced throughout an otter's range, about 40 to 70 m (131–230 ft.) apart.

These stations can be ten times more common along the coast than further inland, where otter movements are channeled along particular routes. Spraint is deposited in conspicuous locations including tree trunks, boulders, trails, and pool edges. Otters spend a great deal of time exploring their own spraint as well as that of others. Each otter's characteristic scent is as unique as a fingerprint and conveys such information as identity, age, sex, and breeding condition. Scent is especially important for marking territorial boundaries.

The scientific name for the sea otter is Enhydra lutris kenyoni. They can live up to 25 years old but the average life span is between 10-12 years. Although the sea otter is the smallest marine mammal, the average adult can be as large as 5 feet in length and weigh up to 70 lbs. The average length of an adult female is 4 feet and average weight is 60 lbs. At birth, sea otters weigh approximately 5 lbs and are 10 inches in length. It spends most of its time in water but sometimes swims to the shore to rest. Sea otters have webbed feet, water repellent fur, and nostrils and ears that close in the water to help them swim. They often float on the water’s surface on their backs. They sleep on their backs often in groups. They sometimes float in large amounts of sea weed that they tangle themselves in to keep them from floating around.

They are also highly intelligent and use rocks to open clams and mussels, their favorite food. They do this by grabbing a rock from the shore, and while laying on their back they place the clam on their stomach and beat it with the rock to open it. This shows their intelligence and ability to even use basic tools. Sea otters are very concerned with hygiene. After eating they wash themselves in the ocean, cleaning themselves with their teeth and paws. Cleaning their coat helps them to maintain the water proofing quality of their fur. Sea otters have thick under fur that forms an insulating layer between them and the cold water. The reason that their fur is so thick is because there are two layers, an undercoat and longer guard hairs.

This system traps a layer of air next to their skin so their skin does not get wet. Sea otters are usually dark brown, often with lighter guard hairs. Alaskan sea otters sometimes have lighter fur on their heads. Sea Otter's have roughly 850,000 to one million hairs per square inch on their body. Sea Otters have two types of hair: stout guard hairs and under fur. The stout guard hairs form a waterproof outer covering and the under fur is very dense. This is very important because unlike other mammals sea otters do not have insulating blubber. From the mid 1700’s to 1911 sea otter furs were very valuable and were sold for roughly $1,125 each.

The sea otter population was greatly affected by this and their numbers dropped dramatically. Sea otters are the only otters to give birth in the water. A female pregnancy can last between 5-8 months per year but they can only have one pup per year. In Alaska, most pups are born during May and depend on their mothers for the first 5 to 12 months of their life. However young otters quickly learn to swim and hunt. Mothers nurture their young while floating on their backs. When they are born they can weigh from 3-5 pounds. Sea otters are social animals, with females and pups spending time together in one group and males in another. The pups fur traps so much air that they cannot dive under water.

When mothers leave the pups wrapped in kelp to hunt, pups bob on the surface of the ocean. The mothers spend a lot of time grooming the pups and most of the time, carry them on their chests. They learn to swim around 4 weeks of age. Sea otters are a threatened species in California due to people hunting them for their beautiful fur. Although they are protected now, they remain vulnerable to oil spills.

They do not have a blubber layer like most other marine animals to protect them. If oil gets in their fur, it loses its insulating qualities and the sea otters soon chills. Several thousand sea otters died in the 1989 Exxon oil spill in Valdez, Alaska. They may also die because of diseases, parasites, boat strikes, entanglements, and toxins. Sea otters are omnivores and they do eat seaweed and other aquatic plants. But they mainly have a carnivorous diet known to eat more than 40 different species of marine animals. They mainly hunt sea urchins, clams, crabs, snails, and small fish in the water and they mainly eat in the morning and afternoon. They have few natural predators but the great white shark and killer whales prey on them. They have to dive to get their food, sometimes up to 250 feet. Adult sea otters can eat 25 to 30 percent of their body weight each day in order to stay warm.

The sea otter has long whiskers growing around their muzzle to detect fish. They can do this by detecting vibrations in the water caused by the fish’s tail. The whiskers help the sea otters hunt in any water condition. Also the molars of the sea otter are very different than other animals. Their molars are for crushing things and not for fish slicing. Also the sea otter doesn’t get sick from drinking salt-water. Sea Otters drink this because it helps eliminate urea from their body. There are three types of species that sea otters are recognized by. The most common sea otter is known as the Asian sea otter and is the largest of the tree sea otter subspecies. It is found around the islands in the Western Pacific.

The southern sea otter also known as the Californian sea otter is found off the coast of California. It is known to have a narrow head and small teeth. The Northern sea otter is native to Alaska and the North West of the Pacific. Sea otters have developed good thermoregulatory adaptations to compensate for heat loss in their cold, marine environment. Sea otters are homeothermic endotherms. Homeothermic endotherms maintain high body temperatures by internal heat production. Sea otter uses their feet to reduce or maximize heat loss when water temperatures are too hot or too cold. When the water temperatures are too cold, sea otters reduce heat loss by floating on their backs with their feet out of the water.

When the sea otter is trying to lose heat, they extend their feet out underwater to maximize their surface area. To preserve body heat sea otters tend to spread out or fold up their feet. The sea otter's feet have areas of increased heat loss because of their actions during movement. When a sea otter swims their feet move faster than the rest of their body, concluding that they suffer more heat loss. In result sea otters have adapted heat exchangers in their feet to balance the loss. In the sea otter’s legs their arteries are completely surrounded by veins, which means that before the arterial blood reaches the leg skin, it is cooled by the blood traveling back to the heart. In conclusion, the blood entering the body is warm and the blood going to the skin is limiting heat loss.

They also have been shown to increase or decrease their buoyancy in response to fluctuation in water temperature. They control their lung capacity to increase buoyancy in cold water and reduce lung volume to decrease buoyancy in warmer waters. Sea otters were hunted for their fur to the point of almost being extinct. In the early 20th century only 1000-2000 sea otters existed. Today over 150,000 sea otters are protected by law. Although the hunt for sea otters has ended, many threats still hinder sea otter recovery. Oil spills are a major concern because once a Sea Otter’s fur is soiled it cannot retain heat and the animal will die. As mentioned earlier, heat is a vital part of a sea otter’s life.

But most Sea Otter mortality today is caused by disease. One of the most common diseases has been the parasite Toxoplasma gondii. This microorganism isn’t found in the ocean environment naturally but it is still killing Sea Otters. Marine biologists have determined that the microorganism is getting into the ocean through cat feces. Help encourage Sea Otter recovery by always land filling (never flushing) kitty litter. If you don’t have a cat, ask a cat owner you know to do the same! Bibliography:

http://wildequity.org/species/18 http://bioweb.uwlax.edu/bio203/s2008/bluske_brit/adaptation.htm http://animals.nationalgeographic.com/animals/mammals/sea-otter/ http://www.seaotter-sealion.org/seaotter/factsseaotter.html http://a-z-animals.com/animals/sea-otter/

http://www.marinemammalcenter.org/education/marine-mammal-information/sea-otter.html?gclid=CJvh59_6jbYCFahlOgodywYALw http://www.bio.davidson.edu/Courses/anphys/2000/Boehm/Habitats.html http://www.seaworld.org/animal-info/info-books/otters/communication.htm