SREL Reprint #2333

Head and body size relationships in polymorphic tiger salamander larvae from Colorado

Judy P. Sheen1,2 and Howard H. Whiteman2,3

 1Harvard-Radcliffe College, Harvard University, Cambridge, Massachusetts 02138
2Rocky Mountain Biological Laboratory, PO Box 519, Crested Butte, Colorado 81224
3Savannah River Ecology Laboratory, Drawer E, Aiken, South Carolina 29802

Introduction: Trophic polyphenism in certain species of salamanders seems to have developed specifically for cannibalism (Powers, 1907; Collins and Holomuzki, 1984; Crump, 1992). The "cannibal" morph of Ambystoma tigrinum larvae is characterized by its larger body size, broader head, and enlarged vomerine tooth patch in comparison with the "typical" larval morph (Powers, 1907; Rose and Armentrout, 1976). These traits provide cannibals with the ability to consume conspecifics as well as large heterospecific prey (Loeb et al., 1994; Maret and Collins, 1996).

In this study, we quantify the relationship between head size and body size in cannibal and typical A. tigrinum larvae from south-central Colorado. Although the relationship between head and body size can be explored using measurements of various head dimensions, gape width (width of head at jaw joint) holds particular relevance. Gape width is an important determinant of foraging success in A. tigrinum because it directly influences the type and sizes of prey that can be ingested (Loeb et al., 1994; Maret and Collins, 1996).

SREL Reprint #2333

Sheen, J.P. and H.H. Whiteman. 1998. Head and body size relationships in polymorphic tiger salamander larvae from Colorado. Copeia 4:1089-1093.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).