Scientists find snake-like venomous dental glands in amphibian species
A team of biologists have reported the first known evidence of oral venom glands in a ringed caecilian, Siphonops annulatus. Found in tropical climates of Africa, Asia and the Americas, they live in burrows of their own making.Updated: Jul 06, 2020 15:45 IST
Think creatures with poisonous or venomous fangs and normally snakes and lizards come to mind. But ever connected toads or frogs with poisonous fangs?
Well, a new study has found evidence of snake-like venomous dental glands in a species of amphibians for the first time. Called Caecilians, these amphibians are often mistaken for snakes because of their long, legless bodies. They look like a cross between a snake and a worm but are related to frogs and salamanders.
Utah State University biologist Edmund ‘Butch’ Brodie, Jr. and colleagues from São Paulo’s Butantan Institute have reported the first known evidence of oral venom glands in a ringed caecilian, Siphonops annulatus. Found in tropical climates of Africa, Asia and the Americas, they live in burrows of their own making.
“We think of amphibians—frogs, toads and the like—as basically harmless,” says Brodie, emeritus professor in USU’s Department of Biology. “We know a number of amphibians store nasty, poisonous secretions in their skin to deter predators. But to learn at least one can inflict injury from its mouth is extraordinary.”
According to Carlos Jarod, a senior author of the study who is the director of Structural Biology Lab at Sao Paulo’s Butantan Institute, caecilians produce two types of secretions – one that is poisonous and mostly in their tail while the head produces mucus to help with crawling through the earth.
“Because caecilians are one of the least-studied vertebrates, their biology is a black box full of surprises,” Jared said.
“It is while examining the mucous glands of the ringed caecilian that I stumbled upon a never before described set of glands closer to the teeth,” says first author Pedro Luiz Mailho-Fontana, a post-doctoral student in the Structural Biology Lab at the Butantan Institute.
Scientists suspect that the ringed caecilian may use the secretions from the snake-like venomous fangs to decapitate its prey.
“Since caecilians have no arms or legs, the mouth is the only tool they have to hunt,” says co-author Marta Maria Antoniazzi, an evolutionary biologist at the Butantan Institute. “We believe they activate their oral glands the moment they bite down, and specialized biomolecules are incorporated into their secretions.
However, the team doesn’t yet know the biochemical composition of the fluid held in the oral glands.
“If we can verify the secretions are toxic, these glands could indicate an early evolutionary design of oral venom organs,” Brodie says. “They may have evolved in caecilians earlier than in snakes.”
The study was published on July 3, 2020, in an issue of iScience.