Spitting cobra
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.
A spitting cobra is any of several species of cobras that can project venom from their fangs when defending themselves.
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.
Species
African:
- Hemachatus haemachatus
- Naja ashei
- Naja katiensis
- Naja mossambica
- Naja nigricincta
- Naja nigricollis
- Naja nigricincta woodi
- Naja crawshayi
- Naja nubiae
- Naja pallida
Asiatic:
- Naja atra
- Naja kaouthia
- Naja sagittifera
- Naja mandalayensis
- Naja miolepis
- Naja philippinensis
- Naja samarensis
- Naja siamensis
- Naja sputatrix
- Naja sumatrana
Other spitting snakes
Some of the Viperidae have been reported to spit occasionally.[4]
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
- ^ 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.
- ^ Berthé, Ruben Andres. Spitting behaviour and fang morphology of spitting cobras. Doctoral thesis, Rheinischen Friedrich-Wilhelms-Universität, Bonn, April 2011.
- ^ 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.
- ^ 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.
External links
- 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"