Figure 1.

(a) Exemplar sea snakes showing variation in head size and forebody-hindbody proportions: top, microcephalic species, Hydrophis atriceps (Vietnam, photo by Arne Rasmussen), and bottom, Hydrophis ocellatus (Queensland, photo by Mahree-Dee White). (b) Maximum credibility tree of 47 species of sea snakes (see also the electronic supplementary material, figure S1). (c) Species were classified by the proportion of burrowing prey in their diet (white = 0–0.33, grey = 0.34–0.69, black = 0.7–1) and the primary burrowing prey type: gobies (blue) and eels (yellow). Cross indicates diet unknown.