Editing Venom (section)

====Reptiles==== 
{{Further|Big Four (Indian snakes)}}
{{Main|Snake venom|Evolution of snake venom}}
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|footer=The venom of the prairie rattlesnake, ''[[Crotalus viridis]]'' (left), includes [[metalloproteinase]]s (example on the right) which help digest prey before eating. 
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Some 450 species of snake are venomous.<ref name="SmithWheeler2006"/> [[Snake venom]] is produced by glands below the eye (the [[Submandibular gland|mandibular glands]]) and delivered to the target through tubular or channeled fangs. Snake venoms contain a variety of [[peptide]] toxins, including [[proteases]], which [[hydrolysis|hydrolyze]] protein peptide bonds; [[nucleases]], which hydrolyze the [[phosphodiester]] bonds of [[DNA]]; and neurotoxins, which disrupt signalling in the nervous system.<ref name=Bauchot>{{cite book |last=Bauchot |first=Roland |title=Snakes: A Natural History |year=1994 |publisher=Sterling |isbn=978-1-4027-3181-5 |pages=194–209}}</ref> Snake venom causes symptoms including pain, swelling, tissue necrosis, low blood pressure, convulsions, haemorrhage (varying by species of snake), respiratory paralysis, kidney failure, coma, and death.<ref>{{cite web |title=Snake Bites |url=http://eclinicalworks.adam.com/content.aspx?productId=39&pid=1&gid=000031&print=1 |publisher=A. D. A. M. Inc |access-date=30 September 2018 |date=16 October 2017}}</ref> Snake venom may have originated with [[gene duplication|duplication of genes]] that had been expressed in the [[salivary gland]]s of ancestors.<ref name="HargreavesSwainHegartyLogan2014">{{cite journal |last1=Hargreaves |first1=Adam D. |last2=Swain |first2=Martin T. |last3=Hegarty |first3=Matthew J. |last4=Logan |first4=Darren W. |last5=Mulley |first5=John F. |title=Restriction and Recruitment—Gene Duplication and the Origin and Evolution of Snake Venom Toxins |journal=Genome Biology and Evolution |volume=6 |issue=8 |date=30 July 2014 |doi=10.1093/gbe/evu166 |pmid=25079342 |pmc=4231632 |pages=2088–2095}}</ref><ref>{{cite journal |last1=Daltry |first1=Jennifer C. |author2=Wuester, Wolfgang |author3=Thorpe, Roger S. |year=1996 |title=Diet and snake venom evolution |journal=Nature |volume=379 |issue=6565 |pages=537–540 |doi=10.1038/379537a0 |pmid=8596631|bibcode=1996Natur.379..537D |s2cid=4286612 }}</ref>

Venom is found in a few other reptiles such as the [[Mexican beaded lizard]],<ref name="Cantrell2003">{{cite journal |last=Cantrell |first=F. L. |title=Envenomation by the Mexican beaded lizard: a case report |journal=Journal of Toxicology. Clinical Toxicology |volume=41 |issue=3 |year=2003 |pmid=12807305 |pages=241–244 |doi=10.1081/CLT-120021105 |s2cid=24722441 }}</ref> the [[gila monster]],<ref name=Mullin2015/> and some monitor lizards, including the [[Komodo dragon]].<ref name=fries>{{cite journal |last1=Fry |first1=B. G. |author2=Wroe, S. |author3=Teeuwisse, W. |title=A central role for venom in predation by ''Varanus komodoensis'' (Komodo Dragon) and the extinct giant ''Varanus'' (''Megalania'') ''priscus'' |journal=PNAS |volume=106 |issue=22 |pages=8969–8974 |date=June 2009 |pmid=19451641 |pmc=2690028 |doi=10.1073/pnas.0810883106 |bibcode=2009PNAS..106.8969F |doi-access=free }}</ref> Mass spectrometry showed that the mixture of proteins present in their venom is as complex as the mixture of proteins found in snake venom.<ref name=fries/><ref>Fry, B. G.; Wuster, W.; Ramjan, S. F. R.; Jackson, T.; Martelli, P.; Kini, R. M. 2003c. Analysis of [[Colubroidea]] snake venoms by liquid chromatography with mass spectrometry: Evolutionary and toxinological implications. Rapid Communications in Mass Spectrometry 17:2047-2062.</ref>
Some lizards possess a venom gland; they form a hypothetical clade, [[Toxicofera]], containing the suborders [[Serpentes]] and [[Iguania]] and the families [[Varanidae]], [[Anguidae]], and [[Helodermatidae]].<ref name="Fry2006">{{cite journal |date=February 2006 |title=Early evolution of the venom system in lizards and snakes |journal=Nature |volume=439 |pages=584–588 |doi=10.1038/nature04328 |pmid=16292255 |last1=Fry |first1=B. G. |author2=Vidal, N. |author3=Norman, J. A. |author4=Vonk, F. J. |author5=Scheib, H. |author6=Ramjan, S. F. |author7=Kuruppu, S. |author8=Fung, K. |author9=Hedges, S. B. |author10=Richardson, M. K. |author11=Hodgson, W. C. |author12=Ignjatovic, V. |author13=Summerhayes, R. |author14=Kochva, E. |display-authors=3 |issue=7076 |bibcode=2006Natur.439..584F |s2cid=4386245 }}</ref>