Sea Otters, Kelp Forests and Web of Life

Sea Life | | January 25, 2010 at 10:26

Kelp Forest Monterey Bay Aquarium

Hello Ocean Lovers!

Every Other Breath is from the Ocean

contributed by Carol Georgi
with underwater photos by Terry Lilley and Sue Sloan.

Please support the movement to establish the Central Coast Extension of the Monterey Bay National Marine Sanctuary.
for more info go to

Here’s more on the sea otter and its role in the Web of Life.

Southern Sea Otter   Enhydra lutris nereis

Perhaps the most familiar image of kelp forests is a picture of a sea otter draped in strands of kelp, gripping a sea urchin on its belly. Both sea otters (Enhydra lutris) and sea urchins (Strongylocentrotus spp.) play critical roles in the stable equilibrium ecosystem. Sea urchins graze kelp and may reach population densities large enough to destroy kelp forests at the rate of 30 feet per month. Urchins move in “herds,” and enough urchins may remain in the “barrens” of a former kelp forest to negate any attempt at regrowth. Sea otters, playing a critical role in containing the urchin populations, prey on urchins and thus control the numbers of kelp grazers.

Without a healthy kelp forest, most marine life, including fish would not be present.
Kelp forests provide habitat for a wide range of marine organisms. These include a diversity of species of smaller
algae, invertebrates, fish, marine mammals, and birds. The kelp forests of the Pacific coast of North America
are estimated to support more than 1,000 species of marine plants and animals.
Read more:

Southern Sea Otter

In our central coast area, according to Terry Lilley, biologist, the sea otters keep the urchin population down and the kelp is thick and healthy. However, in southern California where there are no sea otters, the urchins have taken over the reef and killed much of the kelp forest!  This action ruins the entire ecosystem.

The following information is from the Monterey Bay Aquarium webpage:

Animal Facts
Sea Otters
* Scientific Name:
Enhydra lutris nereis
* Habitat:
Kelp Forest
* Animal Type:
Marine Mammals
* Diet:
crabs, snails, urchins, clams, mussels and other invertebrates
* Size:
to 4 feet (1.2 m) and up to 50 pounds (23 kg) for females and 70 pounds (32 kg) for males
* Range:
California: From Half Moon Bay in the north to near Santa Barbara in the south.
* Relatives:
weasels, skunks, river otters; Family: Mustelidea (sea otters are the only exclusively marine member of this family)

Gargani with sea urchins

Conservation Natural History
To stay warm in chilly ocean waters, otters wear the world’s densest fur. At its thickest, this two-layer fur is made up of more than a million hairs per square inch. (You’ve probably got 100,000 hairs or less on your whole head!)
To keep their luxurious coats waterproof, otters spend many hours a day cleaning and grooming. Such good grooming coats their fur with natural oils from their skin and fluffs it with insulating air bubbles.

Sea otters once thrived from Baja California to the Pacific Northwest of North America through Alaskan and Russian waters and into Japan before hunters nearly exterminated them in the 1700s and 1800s. The California population has grown from a group of about 50 survivors off Big Sur in 1938 to just over 2000 today. Although their numbers have increased, sea otters still face serious risks: oil from a single tanker spill near San Francisco or off the central coast could wipe out the entire California sea otter population.

Cool Facts
An otter may hunt on the seafloor, but always returns to the surface to eat. Floating there on its back, it uses its chest as a table. (And if dinner’s a crab or clam, the otter may use a rock to crack open its prey.)
An otter’s coat has pockets—flaps of skin under each front leg. An otter uses them to stash prey during a dive, which leaves its paws free to hunt some more.

To learn more with video and podcast, go to the Monterey Bay Aquarium webpage:
Video: One of the aquarium’s staff aquarists talks while training otters.
Podcast: Don’t flush: How kitty litter is hurting sea otters.
Learn More: Saving sea otters, learn about the aquarium’s sea otter research and conservation program.
Also, view the kelp forest

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