Plumbeous Water Snake (mildly venomous)
Description: A medium-sized stocky snake, averaging 35-45 cm in total length, exceptionally reaching 61 cm. Olive-green above. Scales smooth. Lower flanks dirty white or yellowish. Head rounded, spade-shaped, slightly wider than neck. Nostrils open on top of snout. Eyes rather protuberant. Ventrals white or yellowish in adults; bright yellow in juveniles, with or without scattered dark dots. A thin black line extends from vent down the sub-caudals to tail tip. Tail short. Possesses two enlarged rear teeth and a weak venom. Resembles the water snake Opisthotropis andersonii but is distinguished from it by its stout body build, smooth scales, large rounded head and lowland habitat.
Habits and habitat: An aquatic lowland species found in stagnant, muddy water such as marshes, shallow ponds, water sumps in cultivated fields or slow-flowing streams. Predominantly nocturnal. Often seen lying motionless in several inches of still water, with the head slightly protruding from the surface. If disturbed, will dive into the muddy bottom. Occasionally found hiding beneath objects. May wander overland on rainy nights. Absents from large deep fish ponds, where E. chinesis is the dominant water snake. Irritable in temperament, will flatten its body and snap viciously when handled roughly. If then placed on the ground, will assume a S-shaped and make a series of jumps in an attempt to escape. Although mildly venomous, its bite causes only slight swelling.
Diet: Eats mainly frogs and tadpoles. Accepts dead fish in captivity.
Reproduction: Viviparous. A captive female gave birth to 5 young. Hatchlings 13.5 to 15 cm in total length.
Distribution: An adaptable and widely distributed species in Hong Kong. Occurs throughout the territory including several islands (Lantau, Cheung Chau, Peng Chau, Lamma, Ping Chau, Shek Kwu Chau). Ranges across southern China including Taiwan, and Southeast Asia.
Diagnostic features: Uniformly olive-coloured back; lower flanks yellow; head slightly wider than neck; protruding eyes; nostrils dorsal; black streak on underside of tail; ventrals cream-white.