The red Mozambique spitting cobra stiffens, fixing its gaze on the victim's face, which is moving backwards and forwards in front of it. For several seconds it remains erect like this; then its head flashes forwards. For an instant the fangs in front of its pale pink throat are visible in its wide-open mouth, as they squirt the venom at high pressure towards the victim. On the plastic visor two red spiral patterns appear. The eyes behind it look surprisingly unperturbed. "I sprayed the visor beforehand with rhodamine," Katja Tzschtzsch calmly explains, "It's a pigment which dyes liquids red. This makes the traces of venom easier to see." In her undergraduate dissertation the trainee teacher investigated what spitting cobras aim at when spitting. "In the literature it often says: they aim at the eyes," her supervisor Dr. Guido Westhoff, junior lecturer in Professor Horst Bleckmann's team, explains. "However, up to now nobody has investigated it." The cocktail of toxins partly consists of nerve poisons, but also contains components which are harmful to tissue. Through a narrow channel in their fangs the snakes can spray the liquid at high pressure similar to a bullet in the barrel of a gun. If they manage to hit an eye, the sensitive cornea reacts with severe stinging pain. In the worst case these burns can ultimately lead to blindness.
As guinea pigs Katja Tzschtzsch used four Mozambique and six black-necked spitting cobras from the animal house in Schloss Poppelsdorf. In her experiments she either stood face to face with them herself protected only by a plastic visor or she used photos. In addition, for both species she recorded the spitting process using a high-speed video camera. "The snakes really do spit only at moving faces," was her first finding; "movements involving the hand elicited no response from any of th
Contact: Dr. Guido Westhoff
University of Bonn