National Geographic : 1986 Feb
THE LAW of the jungle - large creatures devour small ones does not always hold in the world of the tide pool. Witness the wentletrap snail, Epitonium tinctum (left, at bottom), here in an aquarium. Only three-eighths of an inch long (one centimeter), it can extend its snout three times the length of its shell. With it, the snail snacks on a green anemone, Anthopleura elegantissima. However, the snail nibbles only the tentacle tips; the anemone survives. Between tides a pool (right) seems frozen in time. Mussels, sea urchins, barnacles, green anemones, and an abalone await an incoming tide's food laden waters. In the center of this marine paisley print lurks a two-spot Octopus bimaculoides. It pierces the shells of crabs and clams to inject a paralyzing toxin into the flesh before eating it. Resembling helmeted aliens on the march, seven-day-old red-abalone larvae, Haliotis rufescens (right, bottom), land on coralline red algae. These minute travelers-twenty could fit on a pinhead-drift as plankton for one to four weeks before settling down. Researchers at the University of California at Santa Barbara found that receptors guide the larvae to biochemical substances secreted by the algae. These chemicals trigger a sequence that causes the larvae to stop swimming and start creeping over the algae in search of food. Soon the larvae metamorphose into miniature versions of their adult form. Abalones and algae benefit. The larvae find a home. The algae are kept clean.