Figure 1.

It is very common for schooling fish to have yellow tails that are in striking chromatic contrast to the surrounding blue water. Transient blue-ON, yellow-OFF ganglion cells fire to the onset of short-to-middle-wavelength light such as that from the blue backdrop of their world and they fire to the offset of longer-wavelength light reflected from the yellow tail of a conspecific. Thus, such cells are ideally suited for triggering movements to keep a schooling fish on track in its pursuit of the fish in front of it. The cell is silenced when the image of part of the yellow tail covers its receptive field as shown. However, it fires vigorously, and could signal corrective motor movements, when the tail moves, exposing the receptive field to the blue background surrounding the fish.