Venomous Snake - Most Venomous Snakes

Most Venomous Snakes

Lists or rankings of the world's "most venomous snakes" are tentative and differ greatly due to numerous factors.

The high variability of LD₅₀ tests is a major problem. This includes the age and reliability of the data, the number of species analyzed, and the testing methods and toxicity scale used. While there have been numerous studies on snake venom, potency estimates can vary, creating overlap and greatly complicating the task. Further, LD₅₀ may be measured through intramuscular, intraperitoneal, intravenous or subcutaneous injections on small rodents, although the latter is the most applicable to actual bites. So, considering the toxicity of a species based on LD₅₀ alone may not accurately estimate the danger of the species to humans as the efficiency of venom delivery is not taken into account. Further, results from different tests may cause confusion, as different toxicity scales are in use.

Apart from the high variability of toxicity tests, the physiological difference between the animals used and humans is another major problem of selecting the most venomous snakes. Mice are the common indicator used to test venom from venomous snakes in LD₅₀ tests so the LD₅₀ results may not reflect the actual effects on humans due to the physiological differences between mice and humans. Many venomous snakes are specialized predators on mice, and their venom may be adapted specifically to incapacitate mice. While most mammals have a fairly similar physiology, LD₅₀ results may or may not be directly relevant to humans.

Moreover, many of these lists only take into account of terrestrial and arboreal snakes and neglect to list those of venom of the sea snakes. Species of sea snakes have been listed to have more toxic venom than even that of the inland taipan and further investigations of some species' venom are needed.

Sometimes, toxicity of snakes is used to determine their danger to humans but this is improper. There are far more factors critical to determine the potential hazard of a snake to humans, including the distribution and behaviour of the species. For example, while the inland taipan is regarded as the most venomous land snake based on LD₅₀, the Big Four snakes cause far more snakebites due to their frequent occurrence in highly-populated areas. Clinical mortality rate is another commonly used indicator to determine the danger of a snake as it, to a certain extent, can reflect truths other than its toxicity on mice, such as the efficiency of venom delivery, the venom yield and the behaviour of the snake when it encounters humans. The bites of black mamba and coastal taipan result in an untreated mortality rate of approximately 100%. Other species clinically known to cause high mortality rates include the common krait, king cobra, etc. Moreover, death time after envenomation can also reflect the danger of bites from a species to humans. Mambas, the king cobra and the coastal taipan are examples of snakes whose bites may result in rapid fatality if untreated. On the contrary, the inland taipan has not caused any human death. However, it should be noted that the death rate or death time resulting from a bite may vary from person to person as the health state of the victim is also determining and thus snakebites from any kind of venomous snakes should be tackled seriously.