“…Among the many stresses of life in the intertidal zone, responding to the threat of predation must often be balanced against the need to carry out basic life functions such as aerobic respiration, feeding, and waste removal. The sea mussel Mytilus californianus Conrad 1837, found along the western coast of North America, must contend with a number of different predators, including sea stars (Paine, ), muricid whelks (Dayton, ), crabs (Hull & Bourdeau, ), lobsters (Robles, Sweetnam, & Eminike, ), sea otters (Estes, Riedman, Staedler, Tinker, & Lyon, ), and bird predators such as oystercatchers (Hartwick, , ). These predators can attack by prying, crushing, or drilling, and the mussel's primary defense is to hold the shell valves tightly closed, cutting itself off from water, oxygen, and food in the process.…”