"Here were creatures so exquisitely fashioned that they seemed unreal, their beauty too fragile to exist in a
world of crushing force."
--Rachel Carson,
The Edge of the Sea, 1955
BATTERED BY SURF PACKING THE FORCE of a 600-mile-per-hour wind and periodically exposed to drying sun and air, marine organisms somehow thrive along the West Coast. Thanks to the California Current, which draws nutrients up toward the shore from deep in the ocean, tidepool species that grab hold of rocky outcroppings can flourish in one or more littoral, or intertidal, zones.
Snail-like periwinkles and flattened, conical limpets cluster in the splash zone, where they must seal their shells to keep their gills wet during the long dry spells between the highest tides. Seemingly stationary, these mollusks actually roam the rocks, grazing on algae with their radula, or coarse tongue.
A few steps closer to the open ocean, aggregating anemones, lined shore crabs, black turban snails, and California mussels crowd the seascape, submerged for only a few hours a day. A bit deeper, colorful ochre sea stars pursue their prey in the mid-intertidal zone. You may find the stars arched over their victim--a mussel, chiton, or barnacle--using their tube feet to wrench the shells as little as 0.1 millimeter apart so that they can extrude their stomach into the opening and start digesting their quarry.
In the nutrient-rich soup of the low intertidal zone, exposed to air only a few times a month, creatures can withstand the strong surf and tidal forces but have the least tolerance for dehydration. Look for purple sea urchins taking shelter in hollows they excavate using their five teeth and sharp protective spines. Wait for the giant green anemone, which recoils when disturbed or dry, to open like a bloom. It captures small prey and paralyzes them with stinging cells on its tentacles. The anemone's tissues also harbor photosynthetic algae that feed their host some of the sugars they produce in exchange for shelter. Some giant green anemones can also thank the algae for their intense emerald hue. As you pore over the explosion of species in these windows to the sea, you can detect a hint of life's tenacity and intricate interconnections. --William and Wendy Dreskin
