Simultaneous tracking of flagellates in real time by image analysis
The hardware and software components are described to track many flagellates simultaneously in real time. The technique is based on on-line digitization of four frames taken at 80 ms intervals and stored in a specialized video memory. The outline and position of each organism are determined by chain coding and followed through the recorded series of images. The movement vectors of all organisms tracked are stored in the form of deviation angles from a predefined stimulus (light or gravity) direction and the distance each organism has moved in the time interval determined by the hardware clock of the computer. Subsequent programs allow one to determine circular histograms of movement directions and velocities in dependence of the movement direction. Examples of several orientation patterns are given for both photoorientation and gravitaxis in the dinoflagellate, Peridinium gatunense.