Anderson's Stream Snake (non-venomous)

Description: A small thin snake, with an average total length of 30-40 cm, but occasionally grows to 50 cm. Olive brown above, with barely perceptible fine, black lines, crossing each scale. Lowermost row of dorsal scales and ventrals pale yellow. The olive brown colour fades into the yellow gradually. Lower labials and chin shields also yellow. Scales weekly keeled. Nostrils open on top of snout.

Habits and habitat: Commonly found in small fast mountain streams in secondary forest. Occurs in even the tiniest trickles. Seems to be absent from large streams. Remains concealed under rocks or gravel in stream beds during daylight hours and emerges at night to forage. Nostrils open dorsally, enabling the snake to breathe with the body submerged and the snout tip barely breaking the water surface. Very docile and never attempts to bite. Occasionally sympatric with O. kuatunensis and Sinonatrix percarinata.

Diet: Probably feeds on semi-aquatic earthworms. Sometimes does well in captivity on a diet of earthworms.

Reproduction: Oviparous. Young snakes 12 cm at hatching.

Distribution: The most widespread Opisthotropis species in Hong Kong. Occurs in the New Territories, Lantau Island and Hong Kong Island. Has recently been reported from Guangdong, China.

Diagnostic features: Olive-coloured above; lowermost dorsolateral scale row and ventrals yellow.