How Can Fly Eyes Be Blind?
WouterThe human eye is a complex structure that can expand its field of vision and focus images from many points at once. By comparison, fly eyes are immobile and spherical. They protrude from the head of a fly. Their ommatidia are very small and do not have a pupil. They have a limited range of vision, but they are excellent at picking up movement and form. They can detect light from a distance of several yards, which is more than enough for an insect.
While human eyes have cones and rods that can take in all the colors of the spectrum, flies do not have this ability. Instead, their eyes have basic receptors that can only see a few wavelengths of light. As a result, they cannot discern between colors. This means that they cannot see as well as we do.
This discovery came about through an analysis of the genetic code of fruit flies. Scientists found that these flies lack an enzyme called Black that recycles the neurotransmitter histamine. This enzyme inactivates the neurotransmitter by binding with an amino acid called ss-alanine. This amino acid then is separated from histamine and transported back into the photoreceptors. Then, another enzyme called Tan binds to histamine and splits it off. The researchers concluded that the enzyme Tan is responsible for the production of the neurotransmitter.
Neurobiologists also studied the flies’ visual system to better understand how they process information about motion. They used an experimental device to measure how flies responded to a rotating striped pattern in a virtual environment. The flies’ optomotor reactions were affected when the lobula plate was blocked. The scientists discovered that the flies had two neural networks that processed information about movement in the environment: one that stabilises the course and another that determines the position of an object in the environment.
