Types of sunbeam snakes

Xenopeltis is the only genus in the family Xenopeltidae, a small and ancient lineage of nonvenomous, primitive snakes native to Southeast Asia. It holds just two recognized species: the wide-ranging Asian Sunbeam Snake (Xenopeltis unicolor) and the more localized Hainan Sunbeam Snake (Xenopeltis hainanensis). The family sits among the basal, fossorial snakes and is best known for the spectacular iridescence of its members, a structural effect produced by the microscopic surface of their highly polished scales rather than by any pigment. The genus ranges across mainland and island Southeast Asia, with the Asian Sunbeam Snake found from southern China and Myanmar through Thailand, the Indochinese peninsula, and into Indonesia and the Philippines, while the Hainan Sunbeam Snake occupies southern China and northern Vietnam. Typical habitats are lowland forests, agricultural land, gardens, and other moist soils where the snakes spend most of their lives underground or under leaf litter and debris.

Sunbeam snakes are easy to recognize as a group. They are stout, cylindrical snakes with a wedge-shaped, slightly flattened head that is barely distinct from the neck, small eyes, and smooth scales that give the body a glossy, almost wet look. In good light the dark brownish or blackish dorsal surface throws off a strong rainbow iridescence, while the underside is typically pale. They are nonvenomous and harmless to people. They lack the long fangs and venom apparatus of dangerous snakes and rely on a constricting, gripping bite to subdue prey. There is no medical danger from these animals, though as with any wild snake the sensible practice is to observe rather than handle and to let the animal move on.

Ecologically, Xenopeltis are nocturnal, secretive burrowers that hunt soft-bodied prey such as frogs, smaller snakes, lizards, and small mammals, overpowering them by constriction. They are egg-layers, producing clutches that hatch into miniature versions of the adults. Their fossorial habits mean they are far more often turned up by digging or plowing than seen moving in the open, and when disturbed they may vibrate the tail and release a musky odor. Because they are inoffensive and feed on rodents and other small animals, they are a benign presence in the gardens and farmland they share with people across the region.