Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 31, Number 3;   March, 2004

Venom common, predates snake evolution

by Danny Kingsley

By personally catching and milking thousands of snakes around the world, Dr. Bryan Fry, from the Austra1ian Venom Research Unit at the University of Melbourne, has shown that even snakes that we think of as non-poisonous have a venomous bite. His results were presented at the annual Fresh Science forum for young scientists being held as part of Australia's National Science Week. Perhaps even more surprising, Fry has found that venoms have been evolving a lot longer that the snakes themselves. "Snake venom developed only one time in evolution, a few hundred million years ago," he said.

To test this theory, he analyzed the 'saliva' of an archetypal 'non-venomous' snake, the rat snake, to see how far back venom components started in the evolution of snakes. The rat snake, which is commonly sold in pet stores around the world, contained the same toxins as a cobra or death adder, and the toxins were just as potent.

Researching snake venom is not without hazards. Fry has traveled the globe looking for representatives of the major snake lineages. In 2002, he milked over 2,000 snakes and was poisoned four times - including suffering a cobra bite. He even suffered an episode of the bends after diving for sea snakes in the remote South Pacific.

Fry was able to use the isolation of the snakes in Madagascar -- which have been separated from all other snakes for between 40 to 150 million years - to compare the venoms with all the other major lineages across the world: the 'non-venomous' snakes, the elapids, and the vipers. He was able to determine the toxins they all shared in common. Snakes originally evolved from heavy-bodied swamp monsters, not dissimilar to modem anacondas, he said. To become. lighter, and more athletic, the snakes needed a new arsenal, and developed venom. "This origin of venom is so far back, it occurred before the snake we commonly think of as 'non-venomous' even showed up on the tree of life," he said. By tracing these against the evolu.tionary tree of snakes, he is able to present the venom of the very first venomous snake.

The implications of the study are far reaching: it show that the number of snakes containing venom is actually 2,700 -- not the 250 previously catalogued as poisonous. And there is also the possibility that new drugs will come from the work.

One industry that will be affected by this finding is the pet snake trade, an industry that is highly regulated in Australia at least. In other, less regulated countries, there have been cases of people being bitten by pet snakes and falling ill.