Intertidal Organisms EZ-ID GUIDES


on this species


Nereocystis luetkeana (Bull kelp)

photo of bull kelp
Copyright © 2007 Jan Holmes


The haptera holdfast of this brown seaweed leads to a long thin stipe which can reach 36m (118 feet) in length.  The sporophyte blades, up to 10m (33feet) long, grow in two bunches attached to a gas-filled bulbous float at the upper end of the stipe.  The bulb, which buoys the photosynthizing blades to the surface, contains a mixture of gases including 10% carbon monoxide.  Nereocystis is an annual kelp but some individuals survive for more than one year.  At maturity the sporophyte blades produce spore patches called sori which separate from the blades and drop to the ocean floor eventually releasing millions of gametophyte producing spores.  Eggs and sperm from the microscopic gametophytes give rise to the following year's giant sporophytes.  Bull kelp growth rates are among the fastest of all photosynthesizing organisms reaching 14-17 cm (5.5-7in) per day.

This page was created by Jan Holmes on 1/6/07.



photo of bull kelp

photo of bull kelp