The Variable Coquina, Donax variabilis Say, 1822, is a small (usually a little less than one inch) and very common local clam that gets its name from the very broad range of colors displayed by the species, within a single population. (The sample shown in the photos was collected within an area of about one square foot on Captiva.) Scientists believe that this extreme polychromism confuses predators of this species, preventing shorebirds from memorizing clear search images of the small clams. Coquinas are known to literally leap out the sand after the passing of larger waves, which they identify by the vibrations they cause.
Photos by José H. Leal.