Tidal Zone Treasures
Tidal Zone Treasures The rocks and pools of the intertidal zone are home to an array of creatures fancifully named for their shapes and colors.
From top First row: red abalone, Cockerell’s dorid, ringed nudibranch, variegate amphissa, grainyhand hermit crab, ochre sea star, cabezonSecond row: red octopus, opalescent nudibranch, mermaid’s cup, smooth iridescent seaweed, San Diego lamellaria, purple sea urchin, hammerhead doto, leather star Third row: red rock crab, calico sculpin, colorful dendronotus, stubby frond nudibranch, rough limpet, calico sculpin Fourth row: red sponge nudibranch, chink snail, woody chiton, nereid worm, syllid polychaete, peanut worm, brown turban snail, red sea fern Fifth row:shield limpet, sea clown nudibranch, red sea fan, monkeyface prickleback, bat star, green rope, red rock crab, flat porcelain crab Sixth row: splendid iridescent seaweed, Farlow’s soft seaweed, blood star, six-armed star, Pacific sea comb, glycerid worm, sea palm, red gunnel, tinted wentletrap, surf grass, red sea cucumber
The sea star—often called a starfish, though it's no more a fish than it is a sheepdog—ranks with the most spectacular creatures of the diverse menagerie inhabiting the shores near Bodega Bay. Big (sometimes a foot across) and obstinately colorful (some are orange, some are purple; no one knows why), the sea star is usually found in a rock fissure sprawled like a discarded toy. But despite its apparent lethargy,Pisaster ochraceus serves as a top predator of the intertidal zone—tiger of the tide pool—though it lacks anything like a brain.
Sarah Ann Thompson, a marine biologist from the Farallon Institute in Petaluma, California, is guiding me over the rugged rocks and through the tide pools of Bodega Head's Mussel Point, 65 miles north of San Francisco. (I, in rain gear, rubber boots, and knee-pads, am trying not to slip on the shiny, slick kelp and end up as fish food.) Thompson stoops to pick up an orange star.
In a bizarre adaptation right out of a superhero movie, Pisaster can, in the span of a heartbeat—or what would be a heartbeat, if it had a heart—rigidify the "mutable tissue" in its normally limp body to transform itself into a structure as solid as bone. It then employs an internal hydraulic system and hundreds of suckerlike feet to grab the shells of a mussel and summon enough force to pull them apart.