Crab clocks rewound.

In response to my advocacy of a circatidal/circadian model to explain behavioral rhythms in Carcinus (1), Palmer (2) raises questions concerning my initial premise, the nature of one of my model parameters, and the form of data analysis that I used. These questions are responded to and it is restated that the circatidal/circadian model of clock control adequately explains characteristics of free-running behavioral rhythms in Carcinus and probably in some other coastal animals, purported to be explained only by the recently formulated circalunidian hypothesis (3).