Dragonflies (Anisoptera) belong to the order of winged insects. They are medium to large insects that are easily recognizable by their long, segmented and very pliable abdomen and the wide wings with which they can fly very skilful. The four wings are not connected to each other, as with many other insects. This allows the wings to move separately from each other and enables the dragonfly to perform remarkable tricks, such as standing still in the air, taking off vertically and even fly backwards. At 20 to 40 beats per second, the wing-beat is much slower than in other, smaller insects. The most striking characteristic of its head are the compound eyes that consist of 10,000 to 50,000 facets. With these eyes they perceive movement, the upper part sees sharply at a distance and the lower part nearby. In order to distinguish light and dark, the dragonfly has 3 single eyes, which most likely function as an optical balance organ. The deformation of its antennae in flight , allows the dragonfly to measure its speed.