Persistent Daily and Tidal Rhythms of Oxygen Consumption in Two Species of Marine Snails

Abstract

The rates of O2 consumption of 2 species of snails, Littorina littorea and Urosalpinx cinereus, were determined more or less continuously over a 3- or 4-week period. The variation from hour to hour or day to day exhibited little indication of any overt daily or lunar cycles. When, however, an analysis of the data was made there appeared evident a persistent daily rhythm of O2 consumption in these species. When an analysis was made to determine the character of any variation of primary lunar frequency, it was found that Urosalpinx possessed a clear-cut rhythm of 12.4 hours or tidal cycles. The maxima occurred just before the times of low tide. A similar analysis of the data for Littorina resulted in the demonstration of the presence of low amplitude cycles of lunar-day of 24.8 hour length. The times of maxima and minima were approximately the times of successive high and low tides.