Thai National Parks

Reptiles of Thailand

Species of Thailand

South Asian bockadam

Thai: งูปากกว้างน้ำเค็ม

Binomial name: Cerberus rynchops, Johann Gottlob Schneider, 1799

The New Guinea bockadam or dog-faced water snake, Cerberus rynchops, is a species of a colubrid snake found in coastal waters of Asia and Australia.

C. rynchops is commonly found in mangroves, mudflats, streams, ponds, tidal pools, on algae patches, and has even been found burrowing into the mud. C. rynchops is rear-fanged and is mildly venomous. An aquatic and nocturnal snake, it feeds mainly on fish and is known to consume eels.

In captivity, it is observed to move in a sidewinding direction on land. In the BBC series 'Life in Cold Blood' it was filmed adapting this sidewinding technique to jump across a mudflat in Singapore ( up until then no snakes were considered able to truly jump ). It also has a prehensile tail that would suggest it could climb mangrove trees. It is now known to give birth to live young, numbering from 8 to 30, either in water or on land.

It is a quite docile, mild-tempered and a hardy snake; in recent years it has become a welcome addition to snake hobbyists in the Philippines. It also owes its popularity to its bright yellow to orange belly coloring, mostly of females.


The visibility of upper jaw, giving it a dog-like appearance. Head long and distinct from neck. Eyes small and beadly, with rounded pupil. Dorsum dark gray, with faint dark blotches and a dark line along the sides of the head, across the yes. Venter cream with two distinct rows of large, diffuse dark gray spots.


Scales are distinctly keeled. Midbody scale rows 21-25. Ventrals 132-160. Subcaudals 49-72.


This is a saltwater-tolerant species found in Australia (North Territory, Queensland, West Australia), New Guinea, Indonesia (Ambon, Babi, Bacan = Batjan, Bali, Bangka, Buru, Butung, Dolak, Enggano, Flores, Goram, Halmahera, Java, Kalimantan, Lombok, Mentawai Archipelago, Nako, Natuna Archipelago, Nias, Riau Archipelago, Roti, Sangihe Archipelago, Saparua, Seram, Simeulue, Singapore, Sulawesi, Sula Archipelago, Sumatra, Sumba, Sumbawa, Talaud Archipelago, Ternate, Timor, We, Western New Guinea, Wetar); Bangladesh, Cambodia, India (including Andaman and Nicobar Islands), Malaysia (Malaya and East Malaysia, including Pulau Tioman), Burma (Myanmar), Philippine Islands (including Palawan, Panay, Luzon), Singapore, Sri Lanka, Thailand and Vietnam.

Race novaeguinea is found in Indonesia (western New Guinea).

Type locality: "Ganjam" (Orissa State, SE India)

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Scientific classification

Cerberus rynchops

Common names

  • German: Hundskopf-Wassertrugnatter
  • English:
    • South Asian bockadam
    • Asian bockadam
    • New Guinea bockadam
    • Dog-faced water wnake
  • Thai: งูปากกว้างน้ำเค็ม


  • Cerberus rynchops, MURPHY & VORIS (2014)
  • Cerberus rhynchops, T.S.N. Murthy (2010)
  • Cerberus rynchops, Harold Cogger (2000)
  • Cerberus rynchops, Merel J. Cox et al. (1998)
  • Cerberus rynchops, Ulrich Manthey & Wolfgang Grossmann (1997)
  • Cerberus rhynchops, John Roscoe Hendrickson (1966)
  • Cerberus rynchops rynchops, Arthur Loveridge (1948)
  • Cerberus rynchops, Malcolm Arthur Smith (1943)
  • Hurria rynchops, Robert Mertens (1930)
  • Cerberus rynchops, Malcolm Arthur Smith (1930)
  • Cerberus rhynchops, Frank Wall (1921)
  • Hurria rynchops, Leonhard Hess Stejneger (1907)
  • Cerberus rhynchops sic, George Albert Boulenger (1894)
  • Cerberus rhynchops, John Anderson (1871)
  • Cerberus rhynchops, Albert Charles Lewis Günther (1864)
  • Cerberus cinereus, Theodore Edward Cantor (1839)
  • Cerberus cerberus, Georges-Frédéric Cuvier (1829)
  • Homalopsis rhynchops, Friedrich Boie (1827)
  • Homalopsis cerberus, Leopold Fitzinger (1826)
  • Homalopsis molurus, Heinrich Boie (1826)
  • Python rhynchops, Blasius Merrem (1820)
  • Coluber cerberus, François Marie Daudin (1803)
  • Hydrus cinereus, George Shaw (1802)
  • Hydrus rynchops, Johann Gottlob Theaenus Schneider (1799)

Conservation status

Least Concern (IUCN3.1)

Least Concern (IUCN3.1)

Cerberus rynchops (adult)

Cerberus rynchops (adult)

Creative Commons Attribution-ShareAlike 4.0 International Thai National Parks

Cerberus rynchops (adult)

Cerberus rynchops (adult)

Creative Commons Attribution-ShareAlike 4.0 International Thai National Parks

Cerberus rynchops (subadult)

Cerberus rynchops (subadult)

Creative Commons Attribution-ShareAlike 4.0 International Thai National Parks

Cerberus rynchops (juvenile)

Cerberus rynchops (juvenile)

Creative Commons Attribution-ShareAlike 4.0 International Thai National Parks

Distribution map of South Asian bockadam, Cerberus rynchops in Thailand
  • Bangkok Coast
  • Chanthaburi Coast
  • Chonburi Coast
  • Chumphon Coast
  • Khao Sam Roi Yot National Park
  • Nakhon Si Thammarat Coast
  • Narathiwat Coast
  • Pattani Coast
  • Phetchaburi Coast
  • Samut Prakan Coast
  • Samut Songkhram Coast
  • Satun Coast
  • Trang Coast

Range map of Cerberus rynchops in Thailand

Important note; our range maps are based on limited data we have collected. The data is not necessarily accurate or complete.

Special thanks to Ton Smits, Parinya Pawangkhanant, Ian Dugdale and many others for their contribution for range data.

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