Snakes are among the most successful and diverse groups of vertebrates. They swim, burrow, glide, climb, and side-wind utilizing a mostly uniform, elongate, limbless body plan. They include almost 3000 living species that inhabit all nonpolar, non-deep-sea environments and range in size from 10 cm (4 in.) to 8 m (26 ft). Prey vary in kind and size from ant eggs to occasional Homo sapiens, and snakes capture prey in a variety of ways, including constriction and envenomation. Snakes also hold a unique position in the human psyche as objects of reverence and loathing. For these reasons, there is tremendous interest in the study of snake evolution.