The Asian Rhabdophis tigrinus snakes have an unusual approach to poisonous toads: after eating the amphibian, they isolate and store some of the toad's toxins in the glands on its back. Later they use this venom to defend themselves against predators – informs the letter “Proceedings of the National Academy of Sciences”. Although it is known, that invertebrates isolate defense venoms from their victims, this behavior is extremely rare among terrestrial vertebrates.
Deborah Hutchinson from the British Old Dominion University in Norfold and her colleagues observed the R.tigrinus snakes, which have glands on the back of their neck filled with e.g.. bufadienolidami – toxic compounds from the group of glycosides. These compounds are produced, inter alia,. through the skin of poisonous toads.
Scientists suspected, that these serpents don't make this themselves “chemical weapons”. They tested their hypothesis, grasping the hoses R.. tigrinus from the districts, where poisonous toads live and from lands, where these amphibians are absent.
Later they analyzed the fluid from the snakes' neck glands. As they observed, snakes living on Kinkazan – one of the Japanese islands, where there are no poisonous toads, did not have bufadienolide in their glands.
Meanwhile, the snakes from the island of Ishima, where there are many poisonous toads, they had a lot of this relationship.
The snakes of Honshu – islands, where toad abundance fluctuates, had different concentrations of bufadienolides.
The results were also confirmed by the breeding of young R.. tigrinus, fed a toad-free or toad-rich diet.
Scientists also showed, that female snakes, having a high concentration of toxins, they can defend their offspring with the use of bufadienolides.
