Investigations on the Skin Toxin of the Adult Rough-Skinned Newt, Taricha granulosa

Abstract

Thirty species of potential predators on Taricha granulosa were tested by injection or force-feeding to determine their susceptibility to adult T. granulosa skin toxin. All species tested were found to be susceptible to Taricha skin toxin. The action of adult T. granulosa skin toxin is identical to that described for tetrodotoxin from the eggs of T. torosa and the puffer fish. Mammals and birds are susceptible to similar relative amounts of toxin; 0.0002 cc of back skin of T. granulosa killed white mice in 10 min. Snakes other than garter snakes were about 200 times more resistant, and garter snakes were 2000 times more resistant than white mice. T. granulosa was self-susceptible to large doses. Garter snakes, Thamnophis sirtalis concinnus, were able to eat adult newts, even though they were killed by injections. Taricha toxin was very stable and did not lose potency over an 11-month period.