Proprioceptor Organs in the Antennules of Squilla mantis

Abstract

THE antennules of Squilla mantis have been shown by Schaller¹ to be principal organs in food capture. They are 4–6 cm long in the adult animals and consist of three segments, the terminal segment bearing at its distal end three long lash-like extensions which are themselves repeatedly segmented. The first three segments of the antennules have relatively few sensory hairs along their lengths but there are numerous fine hairs on the terminal lashes². The basal joint of the antennule allows the whole appendage to move in any direction, but the joints between the first and second, and the second and third, proximal segments allow movement in only one plane, that is lateral outward flexion from the extended position. The animals normally hold the antennules extended laterally but will point them forwards at objects brought into their visual field¹.