The Sea otter is a member of the weasel family. Southern sea otters are smaller than those found in northern climates. They are approximately 4 feet long. Females usually weigh about 45 pounds and males weigh about 65. Their fur coats are thicker than any other animal. Unlike other sea mammals, they do not have a layer of blubber. This makes them especially vulnerable to oil spills. If the otter’s fur is coated with oil or another substance, they are at high risk of dying from exposure.

Sea otters have a lung capacity 2.5 times the size found in land animals of the same size. Sea otters breed year round. They have a gestation period of 6-8 months and females give birth to a single pup.

Their diets consist of approximately 40 different types of marine invertebrates. They typically dive to 180 feet deep looking for food, but can dive as deep as 330 feet. They must eat food equivalent to 20 25% of their body weight to maintain a high level of internal heat production

Sea otters help maintain a healthy kelp ecosystem by limiting the number of shellfish that feed on kelp. This promotes the growth of kelp forests that are larger and more productive. Kelp beds provide habitat for fish and other invertebrates. .

Otters spend a large portion of their time grooming their fur. This forces air bubbles next to their skin. Air bubbles help keep them warm and provide buoyancy. Sea otters are the only animals known to use tools with the exception of primates. They use rocks, shellfish and occasionally man made items to pry their prey from rocks.

At one time, the California sea otter population was estimated to be between 16,000 to 20,000. The fur trade of the 18th and 19th centuries were devastating to sea otter populations. The sea otter was believed to be extinct in the early 1900s. A very small population was found be living of f Big Sur coast in 1938. This population has slowly grown and was about 2,400 in 1995. Between 1995-1999, the sea otter population declined 4 out of 5 years. There are currently only about 1,950 sea otters alive.

The California sea otter was listed as threatened under the Endangered species act. Oil spills are the number one threat to sea otters. Oil mats their fur and impairs insulation, causing hypothermia. They ingest the oil when they groom their fur, causing damage to their organs.

Disease is another threat. Pollution is a problem, and contributes to the cause of some diseases. Toxoplasma gondii causes protozoal encephalitis in sea otters. It is getting into the marine ecosystem through cat litter that is improperly disposed of. Pesticides and other chemicals are also a problem, especially in agricultural areas.

Other threats include loss of habitat, fishing nets and shootings.

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