Fig. 3. Example of a trial in which a crab fully compensated for disk rotation. (A) Transverse axis of the crab's body (inset), digitized at 200 ms intervals, shown from the start of disk rotation until the crab reached home. Numbers are in seconds after rotation began. Large tinted circle, rotating disk; white circle, position of crab when disk rotation started; blue circle, position of crab when rotation disk ceased. (B) Orientation and bearing of crab and disk over time. Compensatory body rotation by the crab was assumed to have ceased at the time indicated by the black arrow. Note the similarity of this body orientation with that at the beginning of the experiment. (C) Crab and disk angular velocity, and crab angular velocity relative to the disk over time. (D) Reconstruction of seven possible home vectors computed by the path integrator, superimposed on the crab's actual path as in A. See text for details.