Dueling Hypotheses: Circatidal Versus Circalunidian Battle Basics

Abstract

The circalunidian-clock hypothesis is a formulation describing the means by which the tide-associated rhythms of intertidal organisms are generated. The postulate was described in a 1995 article in this journal (12:299–310). A recent paper published here (13:153–62) by Prof. Ernest Naylor challenges the validity of this hypothesis and presents an alternate he calls the “circatidal/circadian clock hypothesis.” His paper first presents a model of his idea and then expresses the model's action in an unusual type of plot of his own invention. From the latter's display, he concludes it describes all the properties used as supporting evidence for the circalunidian-clock idea and thus discredits that hypothesis.

Here, I present my analysis of his model and discuss its usefulness to the field. I find that his Naylor plot does not represent his model, and that his hypothesis mainly explains only data he has obtained for his favorite research subject, the crab Carcinus. I built a model similar to his and show that it produces a compact plot nothing like the one he reported. Finally, I believe that the circalunidian-clock hypothesis–which was not at all endangered by the Naylor paper–is clearly the best explanation at this time for the control of organismic tide-associated rhythms. (Chronobiology International, 14(4), 337–346, 1997)

Key Words:

• Chronobiology
• Tidal rhythms
• Intertidal animals
• Circatidal clock
• Circalunidian clock
• Circadian clock