Coloured scanning electron micrograph (SEM) of a Fruitfly (Drosophila melanogaster) head that was cut open with a Focused Ion Beam (FIB) Microscope. Fruitflies are widely used in genetic experiments, particularly in mutation experiments, because they reproduce rapidly and their genetic systems are so well understood. Wildtype (i.e. normal) Fruitflies have two compound eyes (red) – one on either side of the head. Each consists of hundreds of rounded single lenses and each single lens sends signals to the fly’s brain where they are combined and form a mosaic map of the visual “outside world”.
Small bristles between the single lenses of the eye make sure it cannot be covered with dust or dirt particles. Genetically manipulated (‘mutated’) Flies can either lack compound eyes completely or have additional eyes on the antennae, legs and other body areas. In 2012, Fruitflies are still the most frequently used model organism in genetics despite the species has already been studied and analyzed for more than 100 years of experimental research.