Common Name: a
Class:
Mammalia
Order:
Carnivora
Family:
Mustelidae
Genus:
Enhydra
Species:
Enhydra lutris
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Taxonomy/Description
Sea otters belong to the weasel
family, Mustelidae, which they share with minks, weasels, badgers,
wolverines, and other otter species, in the Mammalian Order
Carnivora. Its scientific name is Enhydra lutris, which means
"otter that lives in the water". Although all otters species spend
time in the water, the sea otter rarely comes on land. It is the
smallest species of Marine Mammal.
Habitat/Diet
The sea otter can be found along the
Pacific Coastline of North America. We observed it's most southern
population on the coast of California. A separate population also
exists along the Aleutian Island chain of Alaska. Sea otters are
specialist feeders who primarily feed on mollusks and crustaceans.
The type of mollusk chosen by a given sea otter is strongly
influenced by what he was taught by observing his mother.

Behavior/Reproduction
The fur of the sea otter is more
dense than that of any other mammal. In some places on its body it
has as many as one million hairs per square inch! To appreciate
this, imagine all the hair follicles from ten human heads compacted
into one square inch. This dense fur allows the sea Otter to keep
warm in the cold waters of the northern Pacific. They blow air
bubbles into their fur to create air pockets around the hair
follicles and these air pockets act as insulators which separate the
sea otter's skin from the cold water. This adaptation is critically
necessary for the sea otter to survive because it is the only marine
mammal without blubber. Unfortunately, the sea otter’s reliance on
its dense fur makes it particularly susceptible to oil spills. The
oil clogs the otter’s fur limiting it from maintaining the necessary
insulating air pockets.

When feeding, sea otters can often be
seen floating on their backs. They characteristically dive to the
bottom of the ocean and pick up a mollusk and a rock. Back at the
surface, they then float on their backs placing the rock on their
abdomens. The otters then repeatedly hit the mollusk against the
rock in order to break open the hard shell and gain access to the
meat inside. Some otters keep the same stone throughout their
entire lives, placing it inside their armpit for later use. The
practice of cracking open mollusks with stones is a form of tool
use. The sea otter is the only non-primate mammal to display tool
use.
Conservation
Sea otters were once hunted
extensively for their dense pelts. When this practice was
discontinued in the mid 20th century, the Southern population of sea
otters made a wonderful recovery from near extinction. However,
the population of sea otter peaked around 1995 and now has been once
again on the decline. The Southern population is estimated at 2000
animals. It is counted twice per year with approximately 200 sea
otters dying between recent counts. Scientists have begun to search
for explanations for this decline and, at first, it was believed
that the otters were starving because their bodies were very thin
when discovered. However, researchers did not find a decline in the
main food sources for the otters. Instead, studies of the dead
otters did show parasites and protozoa, particularly Toxoplasma, in
levels higher than in healthy sea otters. This suggests a weakened
immune system is the cause. It has been hypothesized that human
pollutants in the water such as PCB’s, DDT and tributylin, a
substance found in boat paint, may be the causes of the otters'
weakened immune system. The rise and fall of southern sea otter
population is a perfect example of how human activities can impact
the lives of marine mammals.