Reactions of the spiny lobster,Palinunis vulgaris,to substrate tilt (I.)

Summary Movements of legs on a tilting footboard during fore-aft and side-side tilts elicit a number of different reactions in the spiny lobster,Palinurus vulgaris. Most prominent among these are the predominantly phasic equilibrium reactions of the antennae in the direction opposite to footboard tilt, and the compensatory phasic and tonic deviations of the eyestalks in the direction of footboard movement. Systematic movements of the abdomen and uropods also take place, and the legs display resistance reactions which oppose board movement. Stimulation of a single leg is sufficient to produce the major components of these responses. After stiffening of the C-B joints reactions fail to appear. Mechanism and functional significance of these reactions are discussed in the context of the relevant biological stimuli.The support of D.M. Neil by the British Council Younger Research Workers Interchange Scheme is gratefully acknowledged. We would also like to express our thanks to Peter Heinecke for the expert work of developing and factoring the electronic control devices, Eberhard Göldner and Jörg Stadier for the skilful construction of the setup. We are furthermore indebted to Russ Fernald for his help with the computer work.