Family : HOMALOPSIDAE
Species : Enhydris enhydris
Maximum Size : 81 cm

The genus Enhydris comprises more than 20 species which occur mainly in Southeast Asia. The range of a few species extends into parts of India, southern China, New Guinea and Australia.

Enhydris enhydris (Rainbow Water Snake) inhabits freshwater habitats including marshlands, rural ponds and rice paddies.

The species is mainly a fish eater, but reportedly also consumes amphibians and other small vertebrates.

In 1996-1997 a study of the ecology of this species, and other aquatic snakes, was undertaken at Ban Tha Hin, at the edge of Thalé Sap (Songkhla Lake) in southern Thailand (Murphy et al, 1999). See figures 1 and 2 for an example snake and habitat from this area.

This snake is easily identified by the two pale stripes running down the full length of the body and tail on either side of the vertebral line: these two stripes converge on the crown.

The body is medium brown to greenish brown, and the head and neck is generally more olive coloured than the body. The belly is pale, with a thin brown line running down the middle.

The head is much narrower than the thickset body, and is quite flattened. The snout is squarish. The eyes are small and located towards the top of the head, and the valvular nostrils are positioned above the snout. The tail is relatively short and tapers quickly.

In Southeast Asia Enhydris enhydris is recorded from Myanmar, Thailand, Vietnam, Peninsular Malaysia, Singapore (where it may have been introduced), Sumatra, Borneo and Java. Outside the region it is recorded from eastern India and neighbouring states, and from southern China.

Fig 1 : Example from a slow-flowing freshwater/brackish  inlet (with mangrove trees) discharging into Thalé Sap (Songkhla Lake) in southern Thailand; the snake was foraging in shallow water amongst tangled aquatic vegetation and organic debris. Its tail is at bottom left of the image, and its head at upper right.

Fig 2 : Inlet to Thalé Sap, (Songkhla Lake), southern Thailand; habitat of the Rainbow Water Snake in Figure 1.

Figs 3 to 5 : Example from a freshwater pond at the edge of marshland, Singapore. This specimen had an estimated total length of 45 cm.

References : H12

Murphy, J. C., Voris, H. K., Karns, D. R., Chan-Ard, T., & Suvunrat, K. (1999). The ecology of the water snakes of Ban Tha Hin, Songkhla Province, Thailand. Natural History Bulletin of the Siam Society, 47, 129-147.