The integration of visual stimuli in the rock lobster

Abstract

Single unit impulses were led off from rock lobster “optic” nerve and compared with those of the crayfish. It was found that the lobster possesses, besides type classes which resemble those of the crayfish, an extra class of movement fibers which react specifically, with little habituation, to approaching objects. In addition, the retina is represented by more fibers in each class than in the crayfish, the numbers still being small (about 24 for the whole retina, as against 14). These fibers have, as in the crayfish, overlapping visual fields and are symmetrical with regard to one or more of the four main eye axes. Rock lobster sustaining fibers differ from crayfish ones in (a) dark discharges, and (b) dependence of surround inhibition on distance. The other class of movement fibers resembles the jittery movement type of the crayfish. The conclusion is drawn that the number of fibers in any class and total number of classes present are correlated with the use the animal makes of visual clues.