Bitia hydroides

Keel-bellied Water Snake bitia hydoroides
Keel-bellied Water Snake near mudskipper hole in Malaysia (Photo by M.A. Muin)

Keel-bellied Water Snake Bitia hydroides
Keel-bellied Water Snake killed in Malaysia by fisherman (Photo by M.A. Muin)

Keel-bellied Water Snake Bitia hydroides
Head shot of Keel-bellied Water Snake (Photo by M.A. Muin)

Keel-bellied Water Snake Bitia hydroides
Close-up of head and scales of Keel-bellied Water Snake (Photo by John Murphy)

English name: Keel-bellied Water Snake
Scientific name: Bitia hydroides
Thai name: Ngu Pak-Kwang Tong San

Description: To 90 cm long. Slender body is slightly flattened vertically, with a short tail that narrows to a point. Head is small and blunt with bulging grey eyes. Body is cream/white turning to yellow on the top, with black bands. Belly is white, with unusual keeled scales.

Similar Species: Dog-faced Water Snake has a darker upper body with clear dorsal/ventral contrast.
Little Wart Snake is heavy-bodied, has a distinctly different head shape, and skin that hangs loosely.
Venomous sea snakes of the Elapidae family can appear similar to this harmless species, though they have blunter, more paddle-like tails that don’t narrow down to an elongated point.

Habitat: This species is only found in coastal river mouths and nearby mudflats, though it may hunt in deeper waters. They are proficient burrowers and may spend most of their time in the mud.

Place in the ecosystem: Eats fish in the mudflats, especially mudskippers (gobies). May be eaten by larger snakes, monitors, crocodiles, large fish, or wading birds.

Danger to humans: Though quite similar to a sea snake in appearance, this species is completely harmless to humans

Conservation status and threats: Less than 200 specimens of the Keel-bellied Water Snake have ever been found. However, those specimens were found over a wide range, and in at least one locality were extremely common (over 100 of the snakes found in a few months). It is currently believed that the Keel-bellied Water Snake is simply difficult to locate rather than rare, but the infrequent observations of the species make it impossible to determine its true abundance. Please contact this website if you have any sightings or photos of this species.

Interesting facts: The Keel-bellied Water Snake has enlarged palentine teeth, an unusual characteristic shared by only one completely unrelated species of snake. The reason behind these enlarged teeth is unknown.

References:
IUCN Red List: Bitia hydroides
The Reptile Database: Bitia hydroides
Morphology, Reproduction, and Diet of the Marine Homalopsine Snake Bitia hydroides in Peninsular Malaysia
Michael Cota, Personal Communication.