The blue-tongue lizard can resist deadly snake venom

A new study has made the surprising discovery that Australia’s blue-tongue lizard is resistant to the venom of the deadly red-bellied black snake. Possibly as interesting, the large monitor lizards that feed on venomous snakes are not resistant. While the effects of venom on humans has been heavily researched, this is not the case with other reptiles. 

“It was a shock discovering that the eastern blue-tongue, along with the shingleback, showed resistance specifically to red black snake venom,” said Nicholas Young, a PhD candidate at the University of Queensland.

“Since their resistance was so specific to only this snake species, it seems these lizards have evolved a special plasma component — known as a serum factor — in their blood.”

“This prevents specific toxins in red-bellied black snake venom from clotting the lizards’ plasma, which would lead to a rapid death in most other animals. This resistance doesn’t mean they’re completely immune, but it would give them a greater chance of survival, allowing them to escape or fight back.”

The scientists tested the venom of seven snakes on the plasma of two species of blue-tongue lizards as well as on the monitor lizards or goanas that hunt snakes. Although it initially seems strange that the blue-tongued lizards were the only animals to show venom resistance, there is an explanation. 

“You’d think that a goanna would be significantly resistant to the venom of any snake it was hunting and eating, but that isn’t the case,” said Dr. Bryan Fry, head of University of Queensland’s venom lab.

“Snake venom can only cause harm to goannas if it’s injected into its body by the snake’s fangs, it can’t be absorbed directly through the skin.”

“Goannas are heavily armored and their scales act like medieval chain mail, with each containing a piece of bone, meaning venomous snakes’ fangs struggle to pierce this armor.”

Each reptile – both the blue-tongue lizard and the goanna – have evolved a response to the snake’s bite. It’s just that in the case of the blue-tongued lizard, there is a direct response to the venom itself, while the goanna never has to worry about the venom at all.   

“These two divergent forms of resistance are fascinating examples of evolutionary novelty,” said Dr. Fry.

The study is published in the journal Toxins.

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By Zach Fitzner, Earth.com Staff Writer