At the western edge of Alaska, the forces of wind, waves, and currents, together with the runoff from the land, combine to form a dynamic, constantly changing, and demanding environment. This area is the most varied and richest of the Earth's environments--it is also the most subject to change. The movements of the tides subject the plants and animals of the region to submersion in salty waters, exposure to air, cycles of drying and warming by the sun and wind, exposure to fresh water in rain, and the violence of Pacific storms.

Seemingly, an area of so many and such contrasting stresses would not be able to support an abundance of organisms; however, intertidal areas all over the world are teeming with rich and varied forms of life, many of them unlike anything found anywhere else. In fact, most of the Earth's life occurs at or near boundaries or convergences--between air and land or in the thin, phosphorescent layer of water at the surface of the oceans. Life is, indeed, a marginal affair.