Overview

Sea otter (Enhydra lutris) is a marine mammal native to the northern and eastern coasts of the North Pacific Ocean. They range from north Japan up to Russia, around Alaska, and down to the central Baja California Peninsula. Adult sea otters typically weigh between 31 and 99lb making them the heaviest member of the weasel family, but among the smallest marine mammals. Sea otters float and swim on their backs, have short front paws and rear large webbed flippers. Sea otters are a social species, female and their pups live in one group and males in another call rafts. They will hold paws and or wrap themselves in sea weed so to not float away.

Sea otters do not have a blubber layer to help keep them warm unlike most marine mammals. Sea otters have the densest fur coat in the animal kingdom, up to 1 million hairs per square inch. Their fur coat is very loosely attached in a couple places to their skin. Sea otters can move their fur coat around to get every single inch of it clean. Rubbing and licking behavior as well as blowing air into their fur helps to maintain the insulating and water repellant properties. Sea otter's skin is completely dry even though they are swimming in water.

Unlike most marine mammals that swallow food whole, sea otters do actually chew their food. Sea otters have very strong jaws and eat mostly hard-shelled invertebrates, including sea urchins and a variety of clams, mussels, and crabs. Sea otters are foragers and will dive to collect invertebrates and also a large rock. Upon returning to the surface, they float on their backs, with rock on stomach. As one of the few animals that uses tool, they use the rock as a surface against which they smash their shelled prey open to get to the soft parts that they can eat. Sea otters have been observed to hammer a shelled prey against a hard surface 45 times in 15 seconds.

Sea otters have a supercharged metabolism which requires them to eat a quarter of their body weight every day to stay warm in chilly waters. Food is broken down into simple nutrients, such as fats and sugars. These nutrients are then transported in the blood and absorbed by cells. Within the cells are compartments called mitochondria where nutrients are converted into ATP - a high-energy molecule that acts as the energy currency of the cell. Sea otters spend 1/3 of their day eating, 1/3 of their day grooming, and 1/3 of their day doing everything else.

Newborn sea otters weigh 3 to 5 pounds and are born with their eyes open, first teeth already emerging, and a full coat of dense fur that enables them to only float. They are, however, completely dependent on their mothers for care and protection. When a mother leaves to go hunt for food, she will wrap her pup in kelp, leaving it to bob on the surface of the ocean like a cork. Mothers spend much of their time grooming their pups and are often observed carrying them on their chest. Sea otter pups nurse when they are pups, and begin to learn to swim at around 4 weeks old. After about eight months staying alongside their mothers learning all necessary survival skills, pups are weaned and on their own.

Sea otters are considered a keystone species because of their critical importance to the health and stability of the nearshore marine ecosystem. They eat sea urchins and other invertebrates that graze on giant kelp. Without sea otters, these grazing animals can destroy kelp forest and consequently the wide diversity of animals that depend upon kelp habitat for survival. Additionally, kelp forests protect coastlines from storm surge and absorb vast amounts of harmful carbon dioxide from the atmosphere.

Sea otters were hunted extensively in the past for their luxurious fur, leading to a dramatic decline in their population. Listed as a threatened species, sea otters are still vulnerable, especially to risk of oil spills. Other threats include disease, parasites, boat strikes, predation attacks, and entanglement. It is always illegal for anyone to touch a sea otter or other marine mammal, which are protected by federal law. Call the following numbers to report the stranding of a live or dead sea otter:

Alaska: 1-888-774-7325

California: 1-805-927-3893

Oregon: 1-800-452-7888

Washington: 1-877-326-8837