Fig. 9. Standard metabolic rate (SMR) at 30°C plotted against body mass M_b for seven species of frequently feeding snakes and 11 species of infrequently feeding snakes. Interspecific allometric equations were generated from least-squares regression analysis of data from Secor and Diamond (Secor and Diamond, 2000), this study, and our unpublished observations. Numbers signify the following species: 1, Thamnophis marcianus; 2, Thamnophis sirtalis; 3, Lampropeltis getula; 4, Coluber constrictor; 5, Masticophis flagellum; 6, Nerodia rhombifer; 7, Pituophis melanoleucus; 8, Morelia spilota; 9, Crotalus cerastes; 10, Lichanura trivirgata; 11, Acrantophis dumerili; 12, Boa constrictor; 13, Python sebae; 14, P. regius; 15, P. molurus; 16, P. reticulatus; 17, P. brongersmai; 18, Eunectes murinus. Note that across the range of body masses compared, infrequently feeding snakes have SMR that are almost 50% less than those of frequently feeding species.