Kelp Fronds and Pneumatocysts

Giant kelp (Macrocystis pyrifera) is the fastest growing plant in the world. It clings to the ocean floor and grows upward toward the surface, buoyed up by gas-filled pneumatocysts. Growth occurs at the tips of the plant — the fronds — which resemble leaves of a terrestrial plant.

Kelp frond showing pneumatocysts (air bladders), Macrocystis pyrifera, San Clemente Island

Kelp frond showing pneumatocysts (air bladders).
Image ID: 03406
Species: Giant kelp, Macrocystis pyrifera
Location: San Clemente Island, California, USA

San Clemente Island is the finest place in the world to swim in a kelp forest. (Kelp is found at many other places in similar temperate waters, but San Clemente’s clean blue water and relatively warm temperatures make it ideal among such places.) Similar to the towering redwood stands of the Pacific Northwest, forests of giant kelp soar above the ocean floor, swaying to and fro with passing ocean waves. These forests are home to fishes, rays, sharks and myriad invertebrates that grow on the kelp itself or the neighboring rocky reefs. When a kelp plant is tall enough to reach the ocean surface, it continues growing and spreads out in a huge flat mat, blocking the sun.

San Clemente Island, California.

Keywords: kelp, Macrocystis pyrifera, giant kelp, kelp forest, underwater photo, pneumatocyst, frond.