Snakes and Venom

obvs super rough draft, formatting and pictures and title to be done later!

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SNAKES AND VENOM

 We all know someone who has a phobia of snakes – and no, I don’t mean that “friend” who has her eye on your man. I’m talking about the legless lizards; long, thin, scaly reptiles who have no need to chew their food, they can swallow their grub whole. These guys have a bad rep, and no wonder – over 2.5 million people around the world are bitten and around 100,000 of those die each year^[1]. It makes sense that ophidiophobia, the official word for being terrified of snakes is ranked as the second most common phobia, with 1 out of 3 of us definitely not a fan^[2]. But is there really a reason to be afraid of these danger noodles?

WHAT MAKES A SNAKE, A SNAKE?

Snakes are easily identifiable – they all share the fact that what they lack in limbs they make up for with fangs, are covered in scales, and will always win in a staring contest thanks to their missing eyelids^[3]. Although they share a lot of the basics in common, snakes have many differences between them. There are over 3 thousand different species of snakes in the world, and just like you and I, they are separated into their own groups or families. This is done using a hierarchy of classification, and it shows just how related each type of snake is to each other, and other animals such as crocodiles, birds, fish, and even us, humans. Each level of the hierarchy is more and more specific, going from domain all the way through to species^[3].

So for example, a common death adder belongs in the class of Reptilia with other scaled animals such as lizards, crocodiles, and turtles. Its lack of limbs places it in the Suborder of Serpentes, and its venomous fangs are fixed in its mouth which places it in the family of Elapidae. Other physical traits and genes further characterize the common death adder into the genus Acanthophis and species antarcticus^[4].

THEY AREN’T ALL DANGEROUS, ARE THEY?

All of the world’s snakes are separated into 20 families, and out of those 20, only 4 families include snakes that are venomous; Atractaspididae, Colubridae, Viperidae, and Elapidae^[5]. ‘Great! That’s not a whole heap, maybe they aren’t that bad’ I hear you say it, but slow down buddy. Of the 3,000 species of snakes around today, roughly 600 are venomous^[6]. This means roughly 20% of different types of snakes are able to deposit venom (also known as envenoming) during a bite causing pain, illness, disability, and worst-case scenario, death.

Each year over 2.5 million people across the world are bitten by snakes, but only a quarter of them envenom their victims^[6].  A good chunk of these happen in regions of the developing world that are nice and warm, think tropical or sub-tropical areas like Southeast Asia, Sub-Saharan Africa, and South America. Almost half of all snakebite deaths happen in India^[1], this is in part due to such a high farming culture in combination with a lack of education and medical treatments such as antivenom, which is quite capable of stopping the effects of venom and saving lives.

It’s a little different across the pond, though. Australia is very well known as the hotspot for deadly animals, and bloody oath so it should. With spiders, jellyfish, octopus, and a very diverse range of highly venomous snakes aptly called Australian Elapids, you would be forgiven for thinking that we have an insane amount of deaths with these being the cause. However, you couldn’t be further from the truth. With an increase of urban areas, education and training, and not to mention plenty of antivenom, Australia manages only a couple of deaths each year despite the mass amounts of deadly wildlife^[7].

 

VENOM DOWN UNDER

The Australian Elapidae are part of one of the most significant and famous families of venomous snakes around the world; and with snakes such as cobras, mambas, sea snakes, and Australian Brown snakes, Death adders, Taipans, and Tiger snakes you can see why^[7]. These highly venomous snakes carry with them a mixture of different toxins which are primarily used to take down and help digest their prey but also defend against bigger, threatening objects aka, us.

Neurotoxins are essentially a poison that does its damage to the nervous system of your body. The nervous system is responsible for passing messages around the body from your brain or spinal cord, you could think of it like the electrical wiring of your body. If you spill water (ingest a neurotoxin) on that system, things start shutting down. This is what happens after venom is passed from an Australian Elapid to your body during a bite. The most common features of envenomation include nausea, pain, blurry vision, fainting, slurring of speech, and flaccid paralysis^[7]. This is where your muscles are unable to contract/move and can be fatal if you don’t seek help, as your diaphragm muscle controls breathing, so kind of important.

Bottom line though many snakes are venomous so its always a good idea to familiarise yourself with first aid techniques, and go straight to a hospital if you have been bitten. Also, if you do have a phobia of snakes Australia isn’t your worst enemy, although farming in India may be.

 

REFERENCE:

(In order of appearance)

1. World Health Organization. (2018). Snakebite FAQ. [online] Available at: http://www.who.int/snakebites/snakebites_FAQ/en/index2.html [Accessed 17 May 2018].

 

2. Polák, J., Sedláčková, K., Nácar, D., Landová, E. and Frynta, D. (2016). Fear the serpent: A psychometric study of snake phobia. Psychiatry Research, 242, pp.163-168.

 

3. Pincheira-Donoso, D., Bauer, A., Meiri, S. and Uetz, P. (2013). Global Taxonomic Diversity of Living Reptiles. PLoS ONE, 8(3), p.e59741.

 

4. Blacklow, B., Konstantakopoulos, N., Hodgson, W. and Nicholson, G. (2010). Presence of presynaptic neurotoxin complexes in the venoms of Australo-Papuan death adders (Acanthophis spp.). Toxicon, 55(6), pp.1171-1180.

 

5. Mengden, G. (1983). The taxonomy of Australian elapid snakes: a review. Records of the Australian Museum, 35(5), pp.195-222.

 

6. Kasturiratne, A., Wickremasinghe, A., de Silva, N., Gunawardena, N., Pathmeswaran, A., Premaratna, R., Savioli, L., Lalloo, D. and de Silva, H. (2008). The Global Burden of Snakebite: A Literature Analysis and Modelling Based on Regional Estimates of Envenoming and Deaths. PLoS Medicine, 5(11), p.e218.

 

7. Jackson, T., Sunagar, K., Undheim, E., Koludarov, I., Chan, A., Sanders, K., Ali, S., Hendrikx, I., Dunstan, N. and Fry, B. (2013). Venom Down Under: Dynamic Evolution of Australian Elapid Snake Toxins. Toxins, 5(12), pp.2621-2655.