Bull kelp (Nereocystis luetkeana) can be seen offshore as a mass of fronds floating on the surface, supported by gas filled floats. Four fronds are attached to each round shaped float that is about 4.7 inches (12 cm) across. The blades are very long with some reaching 13 feet (4 m) in length. Bull kelp is an annual seaweed that can grow seven inches (17 cm) in length per day. The bull kelp holdfast is highly branched and anchors the seaweed to large rocks on the ocean floor. This holdfast (haptera) can be up to 15.7 inches (40 cm) across. The kelp forest is an amazing environment and home to a multitude of species. It also is a sight to behold underwater on a bright day with sunlight streaming through the fronds. Bull kelp can grow up to 118 feet (36 m) in length, with a range from southern Alaska to central California.
References:
Brietzke, Chanda and Fretwell, Kelly. “Bull Kelp, Nereocystis luetkeana” Biodiversity of the Central Coast, University of Victoria, 2016, https://www.centralcoastbiodiversity.org/bull-kelp-bull-nereocystis-luetkeana.html
Druehl, Louis and Clarkston, Bridgette. Pacific Seaweeds – A Guide to Common Seaweeds of the West Coast. Madeira Park: Harbour Publishing, 2016.
