A Brazilian biologist has used an unusual method to research the biting behavior of poisonous snakes: João Miguel Alves-Nunes from the Butantan research center in São Paulo used a specially made protective boot to lightly kick Jararaca lance vipers – the most widespread species of poisonous snake in southeastern Brazil – over 40,000 times, as he and his team report in the specialist journal “Scientific Reports”.
This species accounts for most snakebites in the region and, with a total of around 20,000 poisonings per year, a significant proportion of the incidents in the entire country. The animals were not injured during the experiments.
Snake behavior is a generally neglected area of research, especially in Brazil, Alves-Nunes told the journal Science. Most studies do not examine what factors cause them to bite.
“If you study malaria, you can study the virus that causes the disease – but if you don’t study the mosquito that transmits it, you will never solve the problem,” he said. “I tested 116 animals and stepped on each animal 30 times.” During the series of tests lasting several days, he stepped on and next to the snakes a total of 40,480 times.
The lance vipers (Bothrops jararaca) were each placed individually in an approximately two square meter arena at different times of the day. After a 15-minute habituation period, the biologist placed the safety boot either directly next to the snake or gently on the head, middle of the body or tail. He felt 100 percent safe and none of the bites penetrated the foam-covered boots.
He was only bitten in one attempt with a rattlesnake. “Unfortunately, I discovered that I am allergic to both the antivenom and snake toxins,” he said. That’s why he had to go to the hospital for a long time.
The study found that the smaller a Jararaca lance viper is, the more likely it is to bite. “In addition, the females are more aggressive and more likely to bite, especially when they are young and during the day.”
The study also shows that females are more likely to bite at higher temperatures, but males are less likely to bite at night – they then prefer to escape with their well-warmed bodies. In addition, the likelihood of a defensive bite is much higher if you touch a snake on the head than if you step on the middle of the body or the tail.
The researchers hope that the results will improve the distribution of antivenoms. These are often sent to larger hospitals, for which some patients have to travel far because they were bitten in places where there was no antivenom. “By combining our data with data from other studies of snake distribution, we can identify the places where the animals are more likely to be aggressive,” Alves-Nunes explained. “For example, warmer locations with a higher proportion of female snakes should be a priority for antivenom distribution.”