Cerberus schneiderii

Dog-faced Water Snake Cerberus schneiderii rynchops
Dog-faced Water Snake (photo courtesy of Michael Cota)

Dog-faced Water Snake Cerberus schneiderii rynchops
Dog-faced Water Snake on mudflats in Pletchaburi Province (photo by Wolfgang Wuster)

Dog-faced Water Snake Cerberus schneiderii Cerberus rynchops singapore
Dog-faced Water Snake on mudflat in Singapore (photo by budak)

Dog-faced Water Snake Cerberus schneiderii Cerberus rynchops singapore
Head shot of Dog-faced Water Snake (photo by budak)

Dog-faced Water Snake Cerberus schneiderii Cerberus rynchops singapore
Dog-faced Water Snake off Singapore (photo by Low Choon How)

Dog-faced Water Snake Cerberus rynchops schneiderii
Dog-faced Water Snakes in tidal water in Singapore (photo by Ria Tan)

Dog-faced Water Snake Cerberus rynchops schneiderii
Dog-faced Water Snake head shot (photo by Ria Tan)

Dog-faced Water Snake Cerberus rynchops
Dog-faced Water Snake eating fish in Singapore (photo by Ria Tan)

Dog-faced Water Snake Cerberus rynchops
Dog-faced Water Snake eating (photo by Ria Tan)

Dog-faced Water Snake Cerberus rynchops
Dog-faced Water Snake hiding in crab hole in Pletchaburi Province (photo by Wolfgang Wuster)

English name: Dog-faced Water Snake (aka “Southeast Asian Bockadam” or “Schneider’s Bockadam”)
Scientific name: Cerberus schneiderii (formerly part of Cerberus rynchops)
Thai name: Ngu Pak Kwang Nam Khem

Description: To 120cm long. Relatively slender, cylindrical body for a water snake. Head is wider than neck. A dark eyestripe passes through the relatively small eyes. Dorsal scales are keeled.  Body is brownish or grayish with dark crossbars, with a venter that is mottled gray and cream.

Similar Species:Keel-bellied Water Snake has a lighter cream-to-yellow body with no clear dorsal/ventral contrast.
Jack’s Water Snake is dark brown with narrow light markings rather than lighter brown-to-gray with narrow dark markings.
Bocourt’s Water Snake has a far thicker body, is darker in color, and typically only found in freshwater settings.

Habitat: This species is found in mangrove mudflats and brackish river mouths, only occasionally venturing upriver.

Place in the ecosystem: Eats fish. May be eaten by larger snakes, large fish, monitors, and wading birds.

Danger to humans: The Dog-faced Water Snake is rear-fanged but its venom is not a threat to humans.

Conservation status and threats: In the past hundreds of thousands of these snakes were collected for their skins, but the species still appears to be quite common where found.

Interesting facts: This species can be incredibly prevalent in the mangrove mudflats. During the daytime none of the snakes will be visible as they hide in crab holes or under water, but in the night at low tide they will cover the landscape. I have had the good fortune of going on boat trips along mudflats at night where dozens of individuals of the Cerberus group could be seen within an hour. One study in Malaysia found a Dog-faced Water Snake occupying every 1-3 meters of shoreline.

References:
IUCN Redlist: Cerberus rynchops
Wild Singapore: Dog-faced Water Snake
Ecology Asia: Dog-faced Water Snake
Diet, feeding behavior, growth, and numbers of a population of Cerberus rynchops
A Photographic Guide to Snakes and Other Reptiles of Peninsular Malaysia, Singapore and Thailand