Potential targets aimed at by spitting cobras when deterring predators from attacking.

When threatened, spitting cobras eject venom towards the face of an aggressor. To uncover the relevant cues used by cobras for face recognition we determined how often artificial targets equipped with or without eyes elicited spitting behavior. In addition, we measured whether and how target shape and size influenced the spitting behavior of cobras. Results show that oval- and round-shaped targets were most effective, while triangles with the same surface area as oval 'face like' targets hardly elicited spitting. The likelihood of spitting depended on neither the presence, the spatial arrangement (horizontal or vertical) nor the surface texture (shiny or matt) of glass eyes. Most likely, cobras do not specifically aim at the eyes of an offender but at the center of the body part closest to them. As this is usually the face of an animal, this strategy will result in at least one eye of the offender being hit most of the time.

Spitting cobras adjust their venom distribution to target distance.

If threatened by a human, spitting cobras defend themselves by ejecting their venom toward the face of the antagonist. Circulating head movements of the cobra ensure that the venom is distributed over the face. To assure an optimal distribution of the venom, the amplitudes of head movements should decrease with increasing target distance. To find out whether cobras (Naja pallida and N. nigricollis) adjust their spitting behavior according to target distance we induced spitting from different distances and analyzed their spitting patterns. Our results show that the spray pattern of spitting cobras is not fixed. Instead the snake matches its venom distribution to the size of the target independent of target distance.