Salamander Skin Toxins 79 



Symptoms caused by i.p. injections of crude N. lewisi skin extract 

 were quite similar to those caused by extracts of Pseudotriton, those of 

 several other species of hemidactyline plethodontids, and two species of 

 Ambystoma, and the high-molecular weight fractions of newt skin 

 extracts (Brandon and Huheey 1981; Huheey and Brandon 1977; Table 

 2). We realize these may be generalized symptons of distress, but they 

 are distinct from those caused by tetrodotoxin toxinosis, and they may 

 be characteristic of protein toxins. 



In the context of symptomology, the skin of N. lewisi is moderately 

 active, in lethality moderately inactive. Without knowledge of the effects 

 of N. lewisi skin secretion on natural predators, it is not possible to 

 interpret its effectiveness in predator avoidance. Both Neill (1963) and 

 Shoop and Gunning (1967) found that Necturus activity away from 

 cover may be limited by predatory fishes, suggesting that, at least 

 against these predators, skin secretions are not noxious. Experiments of 

 palatability to a variety of potential predators are clearly called for. 

 Antipredator mechanisms have been studied mainly in terrestrial species 

 in which the action of noxious and toxic skin secretions has been rein- 

 forced by defensive postures and, often, aposematic coloration, vocali- 

 zation, and biting (Brodie 1977, 1978). Antipredator mechanisms of 

 permanently aquatic species have not been examined in detail, although 

 some are known to produce noxious and toxic skin secretions (e.g., 

 Cryptobranchus alleganiensis , Brodie 1971; Nickerson and Mays 1973; 

 and Andrias japonicus , pers. observ.). 



ACKNOWLEDGMENTS.— This work was supported by NSF grants 

 BMS74-14371 and DEB78-05959. We are grateful to Anthony Paparo 

 for the use of his laboratory facilities. Alvin L. Braswell, N.C. State 

 Museum, kindly made the specimens of Necturus available for study. 



LITERATURE CITED 

 Brandon, Ronald A., and J. E. Huheey. 1981. Toxicity in the plethodontid 



salamanders Pseudotriton ruber and Pseudotriton montanus (Amphibia, 



Caudata). Toxicon 79:25-31. 

 , G. M. Labanick and J. E. Huheey. 1979a. Learned avoidance of 



brown efts, Notophthalmus viridescens louisianensis (Amphibia, Urodela, 



Salamandridae), by chickens. J. Herpetol. 75:171-176. 

 , and 1979b. Relative palatability, defensive 



behavior, and mimetic relationships of red salamanders {Pseudotriton 

 ruber), mud salamanders {Pseudotriton montanus), and red efts {Notoph- 

 thalmus viridescens). Herpetologica 55:289-303. 

 Brodie, Edmund D., Jr. 1968a. Investigations on the skin toxin of the red- 

 spotted newt, Notophthalmus viridescens viridescens. Am. Midi. Nat. 

 50:276-280. 



