[Sensitivity of Nereis virens polychaetes to mechanical oscillations in water]

Food and escape reactions of Nereis virens to oscillations of a ball 2 mm in diameter in water have been studied. These antagonistic reactions differ significantly by the range of ball oscillations which evoked them. The range from 10 to 30 Hz appeared to be optimal for food reaction, and the range above 40 Hz -- for escape reaction. Worms are able to detect a ball from a distance of 12--13 mm at optimal oscillation frequency 30 Hz. Possible receptor mechanisms providing these types of reaction are discussed.