Rotation Experiments with Blind Goldfish

ABSTRACT Blind goldfish react to rotation at constant angular velocity by swimming against the direction of rotation so as to maintain, on the whole, the same orientation or bearing relative to earth. The lowest angular velocity to which the fish appear to react is below 10°/sec. For the best performers the threshold is about 3°/sec. The stimulus to which the fish responds is not one of contact, initial swirl or water current (when the turntable gets under way), variation in turntable velocity or centrifugal force. The semicircular canals are probably the sensory channels through which a fish is able to detect rotation at constant velocity and the mechanical stimulus to which it responds is probably an angular acceleration. How the fish becomes aware of angular accelerations during rotation at constant velocity is not yet understood.