A number of neutral marine steroids such as desmosterol, campesterol,
brassicasterol, gorgosterol, and other trace steroids were isolated fr
om the coelomic fluid of ripe Nereis succinea and checked for biologic
al activity as sex pheromones on swarming specimens of Platynereis dum
erilii and Nereis succinea. No significant influence of synthetic gorg
osterol or a natural extract of gorgosterol or the other identified st
eroids on the swarming behavior was observed.