ABSTRACT
Behavioural thresholds to several amino acids and related compounds were determined for the brittle star Ophiura ophiura. Brittle stars are most sensitive to sarcosine and glycine. Estimated thresholds to sarco-sine ranged from 3x10-9 to 3x10-7 mol/l for different animals whereas thresholds for glycine were from 2x10-8 to 10- mol/l. The detection of urea and L-isoleucine also occurred below 10-7 mol/l. All other amino acids were detected only at concentrations above 10-6 mol/l. It was not possible to find behavioural thresholds for acetylcholine iodide and its analogs.
