An international team, including scientists from the University of Queensland, made the discovery by studying the composition of spitting cobra venoms from three groups of snakes — Asian spitting cobras, African spitting cobras, and rinkhals.
Co-authors Professor Irina Vetter and Dr. Sam Robinson from UQ’s Institute for Molecular Bioscience are among the team that demonstrated the defensive mechanism had developed as a dominant genetic trait. Dr. Robinson said:
“The fangs of these snakes are adapted to spray venom as far as 2.5 metres — the venom is aimed directly at the face, specifically the eyes, causing intense pain and can lead to the loss of eyesight.”
Professor Vetter said the snakes had independently evolved the ability to spit their venoms at enemies:
“We tested how venom components affected pain-sensing nerves and showed that spitting cobra venoms are more effective at causing pain than their non-spitting counterparts.”
The three different groups of venom-spitting snakes had increased production of an enzyme toxin, phospholipase-A2, which works cooperatively with other venom toxins to maximize pain.
Lead author Professor Nick Casewell from the Liverpool School of Tropical Medicine said venom spitting was ideally suited to deterring attacks from humans:
“It is intriguing to think that our ancestors may have influenced the origin of this defensive chemical weapon in snakes.”
Professor Vetter and Dr. Robinson are pain researchers, studying the molecular mechanisms of pain with the goal of developing new and more effective painkilling drugs. Dr. Robinson said:
“Pain-causing toxins from animal venoms can be useful tools to help us understand pain signalling at a molecular level, and are helping us to identify new targets for future painkillers.”
Provided by: The University of Queensland [Note: Materials may be edited for content and length.]