A Mozambique Spitting Cobra (Image 1).
Evidence of venom systems has been found in fossils of Sinornithosaurus (Gong, et al., 2010) and an ancestor of the shrews (Fox & Scott, 2005). These animals had grooves in there teeth that conducted venom from a gland to the tip of the tooth so that it could be injected into the prey. Gila Monsters and Bearded Lizards also have grooves in their teeth that conduct venom; however, their venom is used to defend themselves against predators, not to subdue prey (Beck, 1990). The venom of stonefish is also used entirely for defence. The venom is injected into the predator through dorsal spines when the stonefish is stood on or bitten. Stingrays also inject venom into their predators through a barb on their tail when they are stood on (Fenner, 2004). Other venomous animals use their venom as a defence, but it is primarily for killing prey.
Stonefish spines (Image 2).
Snakes and spiders use fangs to inject their prey with venom (Calvete, et al., 2009). The fangs have an opening on the dorsal side of the tip and venom flows from the gland to this opening to be injected into the prey. Scorpions have a similar structure on their tails (Politi, et al., 2012). Cone shells use barbs soaked in venom to kill their prey and to attack predators. The venom of some cone shells leads to respiratory paralysis and death (Fenner, 2004). Box jellyfish hunt by using nematocysts that discharge venom when they come into contact with an animal. The death of prey is instantaneous to avoid harm coming to the jellyfish (Sutherland & Nolch, 2000). Blue-ringed octopuses bite their prey and inject them with a salivary toxin that acts as venom (Fenner, 2004). Vampire bat venom isn't used to subdue prey, but it is used to make feeding easier by anaesthetising the area and thinning the blood (Ligabue-Braun, Verli, & Carlini, 2012). There is a struggle between venomous animals and their prey and predators to get the upper hand. The prey and predators of venomous animals become more tolerant to venom, causing venomous animals to increase the potency of their venom (Casewell, et al., 2013). Another use of venom is for male-male competition during mating season.
A blue-ringed octopus (Image 3).
Male platypi fight for the right to mate with females during the breeding season. They use their barbs to puncture the other males and to inject them with a pain-inducing venom (Ligabue-Braun, Verli, & Carlini, 2012). Slow lorises also use venom for this reason, as well as deterring predators and killing external parasites (Nekaris, et al., 2013).
A platypus (Image 4).
Venom is used by us to create antivenom to treat venomous attacks and for medical purposes, such as the development of heart attack and stroke medication (Ligabue-Braun, Verli, & Carlini, 2012). Hopefully, by studying venomous animals and their venom, more uses of venom can be established (Calvete, et al., 2009).
References
Beck, D. (1990). Ecology and Behavior of the Gila Monster in Southwestern Utah. Journal of Herpetology , 54-68.
Calvete, J. J., Sanz, L., Angulo, Y., Lomonte, B., & Gutierrez, J. M. (2009). Venoms, venomics, antivenomics. FEBS Letters , 583 (11), 1736-1743.
Casewell, N. R., Wüster, W., Vonk, F. J., Harrison, R. A. & Fry, B. G. 2013. Complex cocktails: the evolutionary novelty of venoms. Trends in Ecology and Evolution 28: 219-229.
Fenner, P. (2004). Venomous marine animals. South Pacific Underwater Medicine Society Journal, 34(4), 196-202.
Fox, R., & Scott, C. (2005). First evidence of a venom delivery apparatus in extinct mammals. Nature, 435, 1091-1093.
Fox, R., & Scott, C. (2005). First evidence of a venom delivery apparatus in extinct mammals. Nature, 435, 1091-1093.
Fry, B.G., Roelants, K., Champagne, D.E., Scheib, H., Tyndall, J.D., King, G.F., Nevalainen, T.J., Norman, J.A., Lewis, R.J., Norton, R.S., Renjifo, C., de la Vega, R.C., 2009. The toxicogenomic multiverse: convergent recruitment of proteins into animal venoms. Annu. Rev. Genomics Hum. G, R., & Scott, C. (2005). First evidence of a venom delivery apparatus in extinct mammals. Nature, 435, 1091-1093.
Gong, E., Martin, L., Burnham, D., & Falk, A. (2010). The birdlike raptor Sinornithosaurus was venomous. PNAS , 107 (2), 766-768.
Ligabue-Braun, R., Verli, H., & Carlini, C. (2012). Venomous mammals: A review. Toxicon , 59, 680-695.
Gong, E., Martin, L., Burnham, D., & Falk, A. (2010). The birdlike raptor Sinornithosaurus was venomous. PNAS , 107 (2), 766-768.
Nekaris, K., et al. (2013). Mad, bad and dangerous to know: the biochemistry, ecology and evolution of slow loris venom. Journal of Venomous Animals and Toxins including Tropical Diseases , 19 (21).
Politi, Y., Priewasser, M., Pippel, E., Zaslansky, P., Hartmann, J., Siegal, S., et al. (2012). A Spider´s Fang: How to Design an Injection Needle Using Chitin-Based Composite Material. Advanced Functional Materials , 22, 2519-2528.
Sutherland, S., & Nolch, G. (2000). Box Jellyfish. Australasian Science , 21 (8), 39-41.
Sutherland, S., & Nolch, G. (2000). Box Jellyfish. Australasian Science , 21 (8), 39-41.
Images
Image 1- http://0.tqn.com/d/goafrica/1/0/U/I/mozambiquespittingcobra.jpg. Accessed on 27/5/14.
Image 2 - http://www.factzoo.com/sites/all/img/fish/stonefish/stonefish-spines.jpg. Accessed on 27/5/14.
Image 3 - http://www-tc.pbs.org/wnet/nature/files/2008/09/610_ag_blue-ringed-octopus.jpg. Accessed on 27/5/14.
Image 4 -http://www.australiananimallearningzone.com/wp-content/uploads/2012/01/Platypus-Photos.jpg. Accessed on 27/5/14.
A good summary. I still find it incredible how diverse venom-producing species are! I’m still intrigued as to how these systems have evolved, why we see convergence and also why we see divergence. Thanks for enlightening me on the mysteries and marvels of venom! I’ve enjoyed reading your posts!
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