Nervous responses from mechanosensory hairs on the antennal flagellum in the lobster,<i>homarus gammarus</i>(L.)

Abstract

Stimulus response characteristics of tactile hair receptors found on the exoskeleton in the antennal flagellum of the lobster were investigated. Two types of hair receptors could be identified. The receptors are small hair sensilla which are highly sensitive to water movement. One type of hair receptor was dually innervated and individual units involved were directionally sensitive. The receptor could produce a position sensitive response and a velocity sensitive response. Another type of hair receptor was a phasic movement receptor. The impulse frequency was proportional to the velocity of displacement of the hair shaft. The frequency response of the sensillum was examined with sinusoidal vibrations at low frequencies; sensory units responded synchronously to stimuli up to the frequency range of 60–70 Hz. The response characteristics observed suggest that the hair sensilla provide information signalling the mechanical displacement, its velocity and its direction.