Endangered Spotlight: California Sea Otter (Enhydra lutrisnereis)

California sea otters. Photo: MojosCoast

By Susanna Beck

Imagine floating on your back amongst a kelp forest in the coastal waters off of California.  As a precaution, you carefully drape a kelp blade over your body to keep you from drifting out to sea while you rest.  You bob gently with each incoming wave and the rhythm slowly rocks you to sleep. 

This is how 50% of the day is spent for the California sea otter, a creature who has stolen the hearts of many observers with its adorable black nose, thick whiskers and playful personality.

Size and Diet

California sea otters are approximately 4 feet in length and males can weigh up to 65 pounds, with females averaging 45 pounds.  During their 10-20 year life span (females live longer than males), sea otters feed on sea urchins, abalone, mussels, clams, crabs and snails.  Amazingly, they eat 20 to 30 percent of their weight in food each day!

Unique Fur

Without a thick layer of blubber, common in most marine mammals, to protect it from the cold Pacific water, the sea otter instead grows the thickest fur in all of the animal kingdom.  Their fur ranges from 250,000 to a million hairs per square inch and includes a two-layered system.  As a result, a layer of air is trapped beneath the fur and their skin itself, never gets wet.  In fact, pups’ fur traps so much air that they cannot swim under water until they reach approximately 4 weeks of age.

Human Threats

Historically, the sea otter’s fur brought with it much unwanted attention.  Humans soon realized the value of the animals’ thick, soft coats and in the early 20th century, fur traders hunted sea otters to near extinction, reducing the worldwide population of almost a million to barely a thousand animals.  Thankfully, with a listing as a federally protected threatened species, the sea otter population has now climbed to over 100,000 worldwide.

Unfortunately, the fur of the sea otter continues to be the subject of another human threat to the species: oil spills.  Since they lack a thick layer of blubber, sea otters are especially susceptible to the harmful effects of oils spills.  An oiled coat means that its fur no longer traps air above the skin to keep the animal warm.  Without another form of insulation, hypothermia quickly sets in during an oil spill.  As a result, during the 1989 Exxon oil spill in Valdez, Alaska, thousands of sea otters were killed.

Behavior

Eating, sleeping, mating, birthing and raising their young in the water, the sea otter rarely leaves the ocean or estuary during their lifetime. 

The sea otter is the only mammal, besides primates, to use tools.  They can often be seen hammering shellfish open with a rock while drifting on their backs.  Sea otters can dive to 330 feet below the surface while foraging for food and frequently use rocks to pry their prey from below.  While searching for other food, sea otters ingeniously store what they have already found in the loose skin folds in their armpits.

Range

Generally, California sea otters are found as far north as Half Moon Bay and as far south as Point Conception; however, there have been recent sightings of sea otters in the Gulf of the Farallones National Marine Sanctuary.  In fact, sea otters were even spotted in the San Francisco bay in 2006 and 2007.

As an icon for coastal California, the sea otter continues to inspire us to ensure the protection of our precious waters.  For years, the sea otter has been making both children and adults smitten with its irresistible charm.  Its outrageously fuzzy fur and witty knack for making use of its surroundings truly make the sea otter the crafty darling of the sea.