Spitting cobra

A spitting cobra is any of several species of cobras that can project venom from their fangs into the eyes of an attacker when defending themselves.

Schematic comparison between sections of spitting and non-spitting cobra fangs.
Spitting cobras on the right.
1: Section of the whole fang in the sagittal plane.
2: Horizontal section through the fang at the discharge orifice.
3: Frontal view of the discharge orifices.
Juvenile red spitting cobra, Naja pallida
Red spitting cobra
Handling of Naja siamensis, using eye protection

Venom

The spitted venom is generally harmless on intact mammalian skin (although contact can result in delayed blistering of the area), but can cause permanent blindness if introduced to the eye; if left untreated it may cause chemosis and corneal swelling.

The venom sprays out in distinctive geometric patterns when muscles squeeze the glands to squirt it out through forward-facing holes near the tips of the fangs.[1] Individuals of some species of spitting cobras make hissing exhalations/lunging movements of their heads when "spitting" from the tongue, and it has been argued that such actions assist in propelling the venom, but research does not support the hypothesis that they play any major functional part except possibly enhancing the threatening effect of the behaviour.[2][3] When cornered, some species "spit" their venom as far as 2 m (6.6 ft). While spitting typically is their primary form of defense, all spitting cobras also can deliver venom by biting.

Most spitting cobras' venoms are significantly cytotoxic, apart from the neurotoxic and cardiotoxic effects typical of other cobra species. The ability to spit venom evolved in cobras three times independently through convergent evolution. In each of these three cases the venom convergently evolved to be more effective at creating pain in mammals to serve as a better deterent.[4]

Species

African:

Asiatic:

Other spitting snakes

Some of the Viperidae have been reported to spit occasionally.[5]

Among several viper species reported to "fling" or even "spit" venom forward in a spray when threatened, the Mangshan pitviper is particularly notable for consistent and well-aimed spraying of its venom.

References
  1. Young, B. A.; Dunlap, K.; Koenig, K.; Singer, M. (September 2004). "The buccal buckle: The functional morphology of venom spitting in cobras". Journal of Experimental Biology. 207 (20): 3483–3494. doi:10.1242/jeb.01170. PMID 15339944.
  2. Berthé, Ruben Andres. Spitting behaviour and fang morphology of spitting cobras. Doctoral thesis, Rheinischen Friedrich-Wilhelms-Universität, Bonn, April 2011.
  3. Rasmussen, Sara; Young, B.; Krimm, Heather (September 1995). "On the 'spitting' behaviour in cobras (Serpentes: Elapidae)". Journal of Zoology. 237 (1): 27–35. doi:10.1111/j.1469-7998.1995.tb02743.x.
  4. Kazandjian, T. D.; Petras, D.; Robinson, S. D.; van Thiel, J.; Greene, H. W.; Arbuckle, K.; Barlow, A.; Carter, D. A.; Wouters, R. M.; Whiteley, G.; Wagstaff, S. C.; Arias, A. S.; Albulescu, L.-O.; Plettenberg Laing, A.; Hall, C.; Heap, A.; Penrhyn-Lowe, S.; McCabe, C. V.; Ainsworth, S.; da Silva, R. R.; Dorrestein, P. C.; Richardson, M. K.; Gutiérrez, J. M.; Calvete, J. J.; Harrison, R. A.; Vetter, I.; Undheim, E. A. B.; Wüster, W.; Casewell, N. R. (2021). "Convergent evolution of pain-inducing defensive venom components in spitting cobras". Science. 371 (6527): 386–390. doi:10.1126/science.abb9303. ISSN 0036-8075.
  5. Wüster, Wolfgang; Thorpe, Roger S. (December 1992). "Dentitional phenomena in cobras revisited: Spitting and fang structure in the Asiatic species of Naja (Serpentes: Elapidae)" (PDF). Herpetologica. 48 (4): 424–434. JSTOR 3892862.
  • Greene, Harry W. (1997) Snakes: The Evolution of Mystery in Nature. University of California Press, Berkeley and Los Angeles, California.
  • Video of an African red spitting cobra spraying its venom
  • Video of an African red spitting cobra feeding
  • Discovery News 'Spitting Cobras' Sharp-Shooting Secrets"
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