Why snakes are poisonous?
Snake venom is a form of saliva loaded with enzymes. The primary purpose is to assist in digestion, it is also used in defence. Many years ago, it was discovered by vets that if a pet cobra had it's fangs removed, then it would develop a lump near the tail caused by constipation and could die if not treated for constipation. Snakes can precisely control the amount of venom being injected. They give each other love bites, very slowly and with affection, An angry bite can be a snap bite or a very angry chewing bite when the aim is to pump as much venom as possible into the victim. The venom consists of blood poisons and nerve poisons, the predominantly blood poison venoms cause internal bleeding as blood capillaries break down. There are examples of viper bite victims in Africa that have lost flesh from arms or legs as areas of flesh have broken down due to enzyme action. The difference in snake venom strengths has everything to do with the choice of natural prey, and the likely resistance to venom acting as an aid to digestion before the meal is swallowed. This has been known by snake handlers for a very long time. Scientists could learn from snake handlers. It is a bit strange that we focus so much on how deadly Australian snakes are. They may have highly toxic venom but fatalities are very rare. World wide deaths from snake bite are hard to accurately determine but estimates range from 20,000 to around 100,000 per year (and probably mostly children working in fields). The majority are in India and SE Asia and typically occur in rice paddies and plantations. That is a lot of people; more than Rabies, about the same as Cholera and much more than Japanese Encephalitis and snake bite has now been recognised by WHO as a neglected tropical disease. And yet I have met plenty of English folk and Americans who happily traipse about India and Asia but are fearful of visiting Australia because of all our 'deadly creatures' - weird stuff.