New research has revealed a previously unknown method used by certain snakes to avoid being killed by their own venom, and their prey has evolved to use the same biological trick.
It works in a manner similar to the way two sides of a magnet repel each other, Associate Professor Bryan Fry from The University of Queensland explains.
Snake neurotoxins have evolved to have positively charged amino acids on their surface, which bind to negatively charged sites on a receptor on animal cells.
However some snakes have evolved to replace a negatively charged amino acid on their receptor with a positively charged one, meaning the neurotoxin is repelled just like when the same side of two magnets are facing each other.
"What we've discovered is a really cool form of mutation where instead of that binding site on the nerve being negatively charged, some prey lineages like the Burmese python, which is a very slow moving terrestrial snake living where there are a lot of snake-eating cobras, have evolved the nerve pocket to be positively charged," he said.
"This is like trying to force two magnets together with the same charge, it's not going to happen."
Researchers have understood that certain animals, such as the mongoose, are resistant to snake venom through a cell mutation that blocks neurotoxins, but this is the first time the magnet-like effect has been observed.
"The reason we were able to discover it is that we got funding from the Australian Research Council a year ago to set up a $2 million biomolecular interaction facility," Dr Fry said.
"That facility is allowing us to do the kinds of assays that would have just been science fiction before, they would have been completely impossible."