interpreted. Chordotonal organs Chordotonal organs detect and transmit distortions in their position/shape in the same way that campaniform sensilla do. They differ slightly at their site of detection. Chordotonal organs, unlike campaniform sensilla, exist beneath the cuticle and typically respond to stretch as opposed to distortion or bending. Their sensory nerve endings attach between two internal points and when those points are stretched, the difference in length is what is detected and transformed into electrical signaling. There are far fewer chordotonal organs at the base of the haltere than campaniform sensilla (on the order of hundreds), so it is assumed that they are far less important for detecting and transmitting rotational information from haltere movements. Role in visual processing Head stabilization Insect eyes are unable to move independently of the head. In order for flies to stabilize their visual fields, they must adjust the position of their entire head. Sensory inputs detected by halteres not only determine the position of the body, but also, the position of the head, which can move independently from the body. Halteres are particularly useful for detecting fast perturbations during flight and only respond to angular velocities (speeds of rotation) above a certain threshold. When flies are focused on an object in front of them and their body is rotated, they are able to maintain their head position so that the object remains focused and upright. Hengstenberg (1988) found that in the roll direction of rotation, the flies' ability to maintain their head position in response to body motion was only observed at speeds above 50 degrees per second and their ability peaked at 1500 degrees per second. When halteres were removed at the bulb (to retain intact sensory organs at the base) the fly's ability to perceive roll movements at high angular velocities disappeared. Halteres and vision both play a role in stabilizing the head. Flies are also able to perform compensatory head movements to stabilize their vision without the use of their halteres. When the visual field is artificially rotated around a fly at slower angular velocities, head stabilization still occurs. Head stabilization outputs due to optical inputs alone are slower to respond, but also last longer than those due to haltere inputs. From this result it can be concluded that although halteres are required for detecting fast rotations, the visual system is adept by itself at sensing and correcting for slower body