Figure 15.

Creatinine levels are well correlated with creatine levels, reflecting their metabolic link; however, they show no obvious relationship to either phylogeny or ecology, suggesting the lack of a functional role in debilitation of prey. It seems reasonable that the elevated levels of these compounds simply reflect the high rate of ATP anabolism and catabolism in the gland, resulting from the demands of protein synthesis. Elapids, red; viperines, green; and crotalines, blue. Taxonomic abbreviations: Apl, Agkistrodon piscivorus leucostoma; Bmo, Bothrops moojeni; Bmu, Bungarus multicinctus; Cc, Cerastes cerastes; Cdt, Crotalus durissus terrificus; Cvv, Crotalus viridis viridis; Ds, Daboia siamensis; Dp, Dendroaspis polylepis; Mss, Micrurus spixii spixii; Ms1–3, Micrurus surinamensis 1–3; Nk, Naja kaouthia; Oh, Ophiophagus hannah; Oo, Ovophis okinavensis; Pe, Protobothrops elegans; Pf, Protobothrops flavoviridis.