Monterey Bay Aquarium Research Institute
Marine Botany

Morphology: Pneumatocysts

Pictured above is Macrocystis integrifolia, a close relative to Macrocystis pyrifera, which grows in the intertidal zone.  Notice the pneumatocysts at the base of the blades.  Pneumatocysts are gas-filled bladders that act as buoys to raise the blades closer to the surface where photosynthesis can occur.  It has been shown that photosynthesis is greatly inhibited at depths due to less light, therefore, it is to great advantage for the giant kelp to create a canopy at the surface and shade out its competitors (Bold 1978).

Above is an image from the Gilbert M. Smith Herbarium.  Notice the pneumatocysts at the base of the blades.  Pneumatocysts are not unique to the giant kelp.  Other kelps, like the bull kelp (Nereocystis luetkeana), also have pneumatocysts for the same strategy.  Bull kelp pneumatocysts are filled a mixture of gases, including CO (Connor and Baxter 1989).

 

Copyright 2001:  James Lopez

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