Report: new research shows that some snakebites can prove to be more lethal than others because of diet, size and environment

Snakes strike fear into humans and other animals alike because of their potent venoms which makes them deadly predators. Indeed, some species, such as cobras, boomslangs and rattlesnakes, have far more venom than they apparently need: in a single reserve of venom, they have the potential to kill thousands of animals and several adult humans.

But some venomous snakes are not as dangerous For example, the marbled sea snake has only a tiny amount of very weak venom, making it effectively harmless to any relatively large animals such as humans. 

Research by scientists from NUI Galway, University of St Andrews, Trinity College Dublin and the Zoological Society of London shows that the potency of a snake’s venom largely depends on what it eats. 

From RTÉ 2fm's Nicky Byrne Show with Jenny Greene, James Hennessy from The Reptile Zoo in Kilkenny on Irish snakes and spiders

The study compared records of venom potency and quantity for over 100 snake species, ranging from rattlesnakes, cobras and the tree dwelling boomslangs of Africa to sea snakes and burrowing asps. The team found strong evidence that venoms have evolved to be more potent toward animals that are more closely related to their diet.

For example, the team found potency in snakes which mainly eat fish, such as the aquatic coral snake, were highest when measured on fish and lowest when measured on mice, which are distantly related to fish.

"These results make sense from an evolutionary viewpoint as we expect that evolution will have shaped venoms to be more efficient at killing the animals that are most often the target of the venom", says lead author Dr Kevin Healy. "You won’t find many mice in the sea so we wouldn’t expect a sea snake to evolve venom that is more effective at killing mice than fish."

From RTÉ Radio 1's Morning Ireland, Kevin Cunningham from the National Exotic Animal Sanctuary discusses the sighting of a snake in Co Meath

The research also showed that the amount of venom a snake has depends on both its size and the environment it lives in.

"Like all substances venom is dosage-dependent," said Dr Andrew Jackson. "Even alcohol, coffee and water can be toxic at high enough volumes so we needed to consider how much venom different species of snake produce and store in their venom glands. We found that big terrestrial species have the most venom, while smaller tree dwelling or aquatic species had the least. This difference may be due to how often a snake encounters its prey in these different environments, with terrestrial species requiring a larger reserve of venom to take advantage of the rarer opportunities to feed."

The results of the study also have potential to aid in our understanding when it comes to human snakebites.

"Snakebites are a major health concern worldwide, with 2.7 million cases each year," commented Dr Chris Carbone. "Understanding how venom evolves may help us better identify the risks to humans from different snake groups, and also potentially from other venomous animals such as spiders, scorpions, centipedes and jellyfish."

The views expressed here are those of the author and do not represent or reflect the views of RTÉ