M I R A C O S T A Q U I K S C I E N C E T E A M

Sea otters are a quintessential

example of a keystone species;

they affect an ecosystem more

than their size and numbers would

suggest. By eating sea urchins

and other benthic (sea floor)

herbivores, sea otters help to keep

the population of those herbivores

and the kelp that they eat

balanced.

One of the major repercussions of

their relocation is the increase in

the sea urchin population. The sea

urchins graze on the holdfasts of

the kelp, causing it to float away

and die. The loss of the kelp, both

a nutrient and a habitat for a

variety of marine organisms,

creates a domino effect on the

marine ecosystem. Areas that do

not have sea otters often turn into

urchin barrens, which have

abundant sea urchin populations,

and no kelp forests.

Sea Otters and their effect on Marine Ecosystems

Mira Costa Quikscience team

Sea Otters

Sea Otters ~Enhydra lutris

ClassificationKingdom: AnimaliaPhylum: ChordataClass: MammaliaOrder: Carnivora

Family: MustelidaeGenus: EnhydraSpecies: E. lutris

Habitat: areas protected from the wind such as

rocky coasts, kelp forests, and barrier reef. They

also live in areas where the sea floor consists

primarily of mud, sand, or silt.

Diet: Eat over 100 different species. Diet

consists primarily of marine invertebrates

including sea urchins, bivalves such as clams

and mussels, abalone, mollusks, crustaceans,

and snails. Otters tend to select larger items

over smaller ones.

Predators: orcas, sea lions, and sharks. (Sea

otters are known to die from shark bites,

however there is no evidence that sharks

actually eat them.)

The ocean’s teddy bears.

Sea Otter Fun Facts

Relationship with HumansPeople have hunted sea otters for food and fur

for thousands of years. However, fur-hunting

expeditions and high demand for their coats

caused a serious decline in the sea otter

population. To illustrate, the Aleut population of

otters was reduced from 20,00 to 2,000 in the

late 1700s.

Currently, the greatest threat to the sea otter

population is oil spills. Oil spills affects sea

otters more than other marine mammals

because they rely on their fur for warmth. When

the fur is soaked with oil, it can no longer retain

air, and the sea otter dies from hypothermia.

The oil can also be ingested and inhaled by sea

otters during grooming which damages their

livers, kidneys, and lungs.

Sewage, predation by orcas, poaching, and

conflicts with fisheries have also negatively

affected the sea otter population.

Ecosystems Benefit from Sea Otter PopulationsThe reintroduction of sea otters would lead to

dramatic ecological benefit. Substantial

improvement in the health of coastal

ecosystems with recovered sea urchin

ecosystems with recovered sea urchin populations

such as British Columbia, the Aleutian and Commander

islands, and the Big Sur. Both kelp forests and rocky

areas with mussel beds benefit from sea otter

populations. The sea otters remove mussels from

rocks, opening up space for new organisms to occupy,

and therefore increasing the diversity of species in the

area.

What you can doDonate to aquariums that support conservation. The

Ocean Project is a network of over 700 aquariums and

zoos that help to protect and conserve the ocean.

www.theoceanproject.org and www.seastheday.org.

Take advantage of volunteer opportunities at Cabrillo.

To become a Sea Ranger, visit the Cabrillo website at

www.cabrillomarineaquarium.org/ or call 310-548-7562

and ask for the Ranger program to sign up.

Check out www.saveseaotters.org to learn other ways

you can help protect sea otters.

Sea otters can eat up to twenty-five to thirty

percent of their body weight each day.

Although fish make up the main portion of

their diet, otters eat different foods during

different seasons including birds and small

mammals.

Otters are the only marine mammals that have

fur instead of blubber. Otters must groom their

coats constantly to keep them from becoming

matted. A grown otter's fur can contain up to

one billion hairs.

Sea otters can stay underwater for up to five

minutes. They have valve-like skin flaps that

cover their ears and nostrils, which allow them

to dive to depths up to thirty-five feet.

A full-grown male sea otter is about 49-99 lbs

in weight and usually 4-5 ft in length. The

females are slightly smaller at an average

weight between 30-73 lbs and a length of 3.3-

4.7 ft.

M I R A C O S T A Q U I K S C I E N C E T E A M

A N D R E W , A U S T I N , C H R I S , E M M A , F E D , R O B B I E , S Y L V I E