Naja nubiae slow motion spitting Credit: © The Trustees of the Natural History Museum, London and Callum Mair |
Researchers at Bangor University School of Natural Sciences, Bangor, Wales believe they have shown that the components of the venom ejected by spitting cobras has evolved on three separate occasions due to the same environmental pressures. The fact that there are components in these cobra's venom that exploit the mammalian pain receptors to give instantaneous pain, suggests that this evolved as a defensive, not an aggressive mechanism, aimed at deterring attacks by mammals.
Contrary to the theory that venoms are adapted primarily to enable snakes to kill prey, in spitting cobras, a venom which causes instant pain, and a delivery system which enables the snake to spray the venom to a distance of up to 2.5 metres towards the eyes of anything which comes too close, suggests a defence mechanism, rather than hunting weaponry.They have also suggested that early hominins may have played a part in this convergent evolution by attacking the snakes.