Figure 42.25 illustrates the pathway of information in the retina. The fovea centralis of the macula lutea receives the most visual information and is primarily made up of cones for color vision and acuity. Moving away from the fovea, the percentage of cones decreases while the percentage of rods increases. Hence, dim light is more easily detected by the rods in the areas away from the fovea. Insects can detect patterns on flowers utilizing ultraviolet sensors .
Pit vipers can detect heat with infrared sensors .
Fish can detect electric fields produced by other organisms. Some migratory birds as well as homing pigeons can utilize the earth's magnetic field to navigate and orient themselves.