Optomotor Reactions of Mantis Under Open-Loop-Condition

Abstract

The optomotor hoad torque of Sphodromantie lineola (Mantodea. Insecta) on a sinusoidally moving stripe pattern respectively a living prey object haae been recorded by means of strain gauges synohronously with pattern movement. In both oases of stimulation amplitude and phase are plotted In a Bode diagramm within the range of 0,3 to 30 rad/s. The plots are different as far as amplitude and phase are more homogeneous on stimulation by stripe pattern and show a marked variability on presentation of the prey object. In general there is a pronounced leading of phase on single object stimulation, in contrast to a phase close to zero on stripe pattern stimulation. The original recordings show a clear difference between the effects of both kinds of stimulation as far as the torque on stripe pattern movement is of continuous, tonic course while on a moving prey objeot it is differentiated into tonio and phasic or saccadic components. An excentrio stationary position of the prey objeot elicits repeated saooades towards the target. These facts affirm the conclusion drawn after former investigations that special insects like mantids fir single objeots in analogy to human fixation but react to periodio patterns in a different manner.