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Giant Kelp - Macrocystis pyrifera
Photo by Kathy deWet-Oleson

Giant kelp forms vast forests that create crucial habitat for many fish and invertebrate species. Kelp has a rootlike structure called a holdfast that wraps around substrate to anchor the growing alga. There are special reproductive blades near the holdfast that produce spores. Many slender stipes are buoyed towards the surface with gas filled bulbs that have wide wrinkled blades at their end. When the kelp reaches the surface it spreads out creating a thick canopy.

Giant Kelp
(Macrocystis pyrifera)

Año Nuevo to Baja California and South America

Rocky subtidal from 3-30 m (10-100’)

Needs sunlight for photosynthesis


The status of this species is representative of the populations within the waters of this Sanctuary only, not global populations.

Quick Fact
Known as the fastest growing alga, giant kelp can grow as much as 0.6m (2 feet) per day.

Learn More
- California State University
- University of California, Santa Cruz