The Biology ofChthamalus Stellatus(Poli)

Abstract

Chthamalus stellatus is a littoral barnacle very similar in habitat and general ecological relations to another littoral barnacle, Balanus balanoides. In those localities where both species flourish they compete considerably for space, and also possibly for food. The fact that B. balanoides settles sooner after the winter storms than does Chthamalus probably favours the former.Chthamalus is characteristically a southern species and Balanus balanoides a northern one, but the north and south ranges of the two species overlap in the British Isles and in France. The determining factor is presumably temperature.Chthamalus is an Atlantic species, and Balanus balanoides is more characteristically a North Sea species. The essential factor in Atlantic water remains unknown, although in respect of a need for Atlantic water Chthamalus resembles Sagitta elegans and intertidalEchinus esculent.