Giant Kelp

Giant kelp

Kelly Moore / NPS

Common Name
Giant Kelp

Scientific Name
Macrocystis pyrifera

Habitat
Rocky reefs up to 100 feet below the ocean’s surface

Additional Information
Giant kelp is the worlds largest species of marine algae. In the United States, it can be found along the west coast, especially around southern California where it grows in dense patches, or kelp forests. Giant kelp can grow at depths of nearly 100 feet, sending fronds upwards towards the surface at a rate of up to two feet per day. Gas bladders, called pneumatocysts, act as floats helping to keep the kelp upright in the water column as it grows towards the sunlight. When it reaches the surface, it spreads out to create a dense surface canopy. Holdfasts, root-like structures that anchor the kelp to the bottom, are excellent hiding places for things like juvenile invertebrates such as sea stars and sea urchins. The blades of giant kelp help provide refuge for many mores species of fish and invertebrates.

Kelp forest in Channel Islands National Park

Kelly Moore / NPS