"Vine snake" is the common name given to a variety of snakes that share certain characteristics — they look like, live like and sometimes act like plant vines. Within the reptile family Colubridae, which groups the world’s majority of snakes, there are vine snake species within several of its genus subdivisions. Vine snakes are venomous, but with one deadly exception, they are only mildly toxic to large mammals. Hypnotically beautiful, some have become popular terrarium pets.
Also called a whip snake, a vine snake typically has a very long and slender body, slightly flattened. Most measure between 2.5-5 feet (0.75-1.5 meters) long, with their tails accounting for more than one-third of the length. Their heads are correspondingly narrow and tapered to a sharply pointed snout. Although most common in the equatorial tropics, there are species that also inhabit temperate, even dry, climates.
Most of the vine snakes of South America are categorized in the genus Chironius. They are commonly called sipos after the Portuguese word for a type of woody vine that climbs tree trunks and forms bridges across the canopy of a rain forest. The snakes are arboreal. Mostly diurnal, though some are also active at night, these methodical predators prey on young birds that are ambushed in their nests by quick strikes. Another hunting method employed by vine snakes is wiggling their tongue to mimic of a worm or insect on a branch to lure frogs and lizards.
Another genus of New World snakes, Oxybelis, ranges further throughout Central America and as far north as the North American Southwest. Befitting their signature camouflage, vine snakes of savannas, chaparral deserts and dry forests are usually brown, and some species are commonly called bronzebacks. A characteristic of Oxybelis is the black color of its oral cavity, which it exposes prominently when threatened.
Morphologically very similar, the genus Ahaetulla, which inhabits India and Asia, comes in various colors and patterns, including iridescent emerald green. Unique to most reptiles, this division of vine snakes has excellent binocular vision. Its pupil is keyhole-shaped, and a grooved channel extends from each eye along the sides of its snout in the fashion of a gun sight. When startled, it might gently sway from side to side, either like a vine in a breeze or like it might be fine-tuning its three-dimensional visual map.
One peculiar species of Ahaetulla feeds on fish, sighting and striking them from branches overhanging water. Other species are known to feed on rodents. The varied diet and exquisite camouflage of this genus has made the vine snake increasingly popular in the exotic pet industry. In part because of critical climate control, however, they are difficult to keep alive in captivity.
The only vine snake capable of killing a human is in the sub-Sahara African genus Thelotornis. As a warning toward a potential threat, these snaked might first inflate the neck region to reveal brightly contrasting colors of skin underneath their otherwise camouflaged scales. Like all vine snakes, Thelotornis is opisthoglyphous, with fangs located toward the back of the upper jaw, just below the eyes.