University of Southern California Sea Grant Program

Help with Kelp

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Some animals like sea otters and sea lions hunt through all areas of the kelp. Sea lions consume vast quantities of fish, and find all areas of the kelp forest to be an abundant "fish market." They find good shopping there!

The sea otter, however, may spend almost its entire life in the kelp bed. While they also eat fish, their favorite meals are two invertebrates: abalone and sea urchins. If the population of sea otters gets too low, the number of sea urchins can easily increase; sea urchins eat kelp. Scientists have found that in Southern California kelp beds that were once inhabited by sea otters have gradually disappeared. Without their natural predators, sea urchins increased in number and moved through the kelp in an "urchin front," eating all the plants in their path. Even when the kelp beds were gone, young kelp plants could not get started due to the hungry urchins. So, the sea otter plays an important role in the health of the kelp forest habitat!

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