Kelp Forest | Nature of America

Hundreds of species live in the kelp forest, a lush undersea ecosystem in which the largest seaweeds, known as kelp, grow as tall as trees. Much like a forest on land, a kelp forest has an upper layer called a canopy, but instead of leafy branches, this canopy contains the topmost fronds of swaying towers of kelp. The largest kelp species extends a hundred feet or more from the canopy down to the seafloor, where its root-like holdfast clings to the rocky bottom and holds it in place.

The stamp pane features a kelp forest in the Monterey Bay National Marine Sanctuary, a federally protected area encompassing 5,322 square miles of ocean off the central California coast. Here, a rich assemblage of marine organisms finds ample food and shelter. One species is especially important to the survival of the kelp forest itself: The sea otter likes to eat sea urchins, spiny kelp-eating creatures that can overgraze groves of kelp when otters are absent.