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143

giant kelp

OLogy Series
biology
card
143

giant kelp

OLogy Series
biology

Think of giant kelp as the Godzilla of the seaweeds. These amazing brown seaweed can grow over 100 feet tall, at a rate of up to two feet a day! Large patches of kelp, called "kelp forests," can stretch many miles along cool coastal waters. These forests are important ecosystems, providing shelter and protection for many marine animals like sea urchins, snails, and crabs.

Forests of the Sea
Today, kelp forests thrive along the coast from northern California to Alaska. But just one hundred years ago, kelp forests didn't grow this far north. One reason the kelp forests have flourished is the general warming trend. But sea otters have also played an important role. What's their key to helping the kelp forests thrive? Sea urchins. You see, sea urchins eat giant kelp -- lots and lots of giant kelp. In fact, it's hard for kelp forests to survive when there are many sea urchins around. But sea otters like to eat sea urchins -- and when otters are nearby the urchins have to hide. By keeping the sea urchins under control, sea otters help kelp forests flourish. This is why over time, both kelp forests and sea otters have extended their range north along the Pacific coast. Now that's working together!

What does kelp use to anchor itself to the bottom of the ocean?

roots

holdfast

suction cups

Are you right?

Correct!

Kelp use a part called a holdfast to anchor itself to the ocean floor -- kind of like the way that roots anchor plants into the ground. But unlike roots, the holdfast doesn't take in nutrients. It just acts as an anchor.

Giant kelp are a marine:

plant

alga

bacteria

Are you right?

Correct!

Giant kelp are a kind of seaweed, which is a marine alga. But like plants, kelp use energy from sunlight to make their own food.

A compound from giant kelp helps make salad dressing, chocolate milk, and ice cream.

Fact
or
Fiction
?

Fact

Many products are made with a substance from kelp called "algin." This compound helps thicken ingredients so that they stick together.

giant kelp
Scientific name: Macrocystis pyrifera
Size: 100 feet long
Habitat: shallow, cool coastal waters in the Pacific
and Indian Oceans
Eaten by: a variety of marine life, such as sea urchins and kelp crabs
Characteristics: can anchor itself to ocean floor; grows like an underwater forest

Image credits: courtesy of Gary McCarthy, underwater-photos.