Effect of temperature and salinity on corporal activities of some echiuran worms

Abstract

Change in temperature did not produce alterations in the weight and/or volume of <i>Achaetobonellia maculata</i>, <i>Acanthobonellia vulgaris</i> and <i>Anelassorhynchus branchiorhynchus</i>, but it did influence the speed of the burrowing cycle and other corporal movements of these animals. Temperature higher than 38ᵒC were lethal. Weight variation was greater in a hyposmotic environment than in a hyperosmotic one; range variation being independent of the size of the animal. <i>A. maculata</i> and <i>Ac. vulgaris</i> showed the capacity to regulate corporal volume in a salinity approximately 28.5 x 10^-3 that of seawater and survived in a salinity 12 x 10^-3 that of seawater, while An. branchiorhynchus regulated its corporal volume in a salinity approximately 16.25 x 10^-3 that of estuarine water and survived in a salinity 12.5 x 10^-3 that of estuarine water. Typical poikilosmotic behaviour depended on the stress intensity to which the echiurans were submitted.