The relationship between temperature and rhythmic cirral activity in some Cirripedia considered in connection with their geographical distribution

Abstract

1. Barnacles can tolerate quite a wide range of temperature without being killed, remain responsive to stimuli over a more limited range, but are fully active only within relatively narrow limits. It is the last range that is most important in determining the fitness of a species to its geographical distribution and the extent of competition between species. 2. During the past ten years work has been carried out on many European and American species from a wide variety of habitats and climates. Activity has been measured as rate of rhythmic beating of the cirri, a temperature-dependent process which is an index to general metabolic rate. 3. It has been possible to show the existence of sub-species or physiological varieties in some apparently widespread species, and to confirm or deny previous assumptions made on morphological grounds as to the validity of species and other taxa. 4. In a few widespread forms little latitudinal or temperature adaptation was found compared with differences related to tide-level and degree of exposure to waveaction. 5. In general the results empasize the importance of physiological data in taxonomy as well as the need for systematic exactness in physiology. © 1964 Biologischen Anstalt Helgoland.