Poisonous Asian Grass Snake
March 25, 2011
Professor: Dr. Deborah Hutchinson
The Asian grass snake (Rhabdophis tigrinus) is an interesting species that sequesters defensive toxins from poisonous toads to become poisonous itself. CCU faculty member Dr. Deborah A. Hutchinson has spent much of her professional career with a group of researchers studying toxin sequestration in R. tigrinus, which is indigenous to eastern Asia. It is known in Japan as the Yamakagashi and can grow to about three feet in length and has an average lifespan of four years.
The toads that are prey to these snakes are toxic to most other species due to the presence of steroids known as bufadienolides. The Yamakagashi is unique in that it tolerates the toxins and stores them in nuchal glands in the dorsal skin of the neck. It then releases the toxins through the skin by arching its neck toward its predators as a defense mechanism. If a predator comes into contact with the fluid in the nuchal glands, the bufadienolides may cause injury to the eyes and lining of the mouth of the predator.
Dr. Hutchinson and her colleagues have conducted dietary experiments to determine the ultimate source of bufadienolides in the Yamakagashi. These snakes were able to survive on toad-deficient diets, but they lacked defensive bufadienolides in their nuchal glands if denied toads. Snakes had various levels of the toxins depending on number of toads consumed. It was also found that mothers could pass ingested bufadienolides on to their offspring to use for protection immediately upon hatching.
In the future, Dr. Hutchinson and her colleagues will be studying how the snakes are able to tolerate bufadienolide toxins as well as the physiology of the system.
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Dr. Deborah Hutchinson