Alfaro et al. (2004) studied the phylogeny and phylogeography of the coastal marine colubrid (Homalopsinae) snake genus Cerberus, a group of rear-fanged water snakes found in Southeast Asia and Australia. Historically, three Cerberus species have been recognized: C. australis (from Australia), C. microlepis (known only from Lake Buhi in the Philippines), and the widely distributed C. rynchops (found from India to Wallacea). However, Allfaro et al. (2004) found that C. australis is highly divergent and probably needs to be excluded from the genus Cerberus to make it monophyletic. Murphy et al. (2012) recognized five Cerberus species: Cerberus rhynchops (southern Asia), C. schneiderii (Southeast Asia and Philippines), C. microlepis (Philippines), C. australis (Australopapuan region), and a newly described species from Micronesia, C. dunsoni.
Cerberus rynchops is associated with tidal mudflats and coastal mangrove forests in Southeast Asia. It is an edge species typically associated with mangrove forest and mudflats along the shores of brackish estuarine and marine coastal situations; however, it is euryhaline and may be found in freshwater as well. Although usually associated with coastal and estuarine mangrove forests and tidal mudflats, it has been reported in hypersaline environments (790 mm Cl) as well as freshwater streams and ponds (see references in Karns et al. 2000). The saltwater tolerance of C. rynchops has been investigated, revealing a rudimentary premaxillary salt gland and salt excretion, the only homalopsine snake known to possess a salt gland (see references in Karns et al. 2000). Dehydrated estuarine C. rynchops discriminate between salt and freshwater, but hydrated snakes do not show a preference for either fresh or saltwater when given an option. Cerberus rynchops is a generalist feeder, taking a variety of fish representing several families, as well as some crustaceans, and possibly frogs and tadpoles. Predators known to feed on C. rynchops include crabs, Tiger Sharks (Caracharhinus caustus), and several raptors, including White-bellied Sea Eagle (Haliaeutus leucogaster), Brahminy Kite (Haliaster indus), and Pariah Kite (Milvus migrans) (Voris and Murphy 2002 and references therein)
- Leviton, A.E., G.O.U. Wogan, M.S. Koo, G.R. Zug, R.S. Lucas, and J.V. Vindum. 2003. The dangerously venomous snakes of Myanmar: illustrated checklist with keys. Proceedings of the California Academy of Sciences 54(24): 407-462."
- Dunson, W. A. & Dunson, M. K. (1973) Convergent evolution of sublingual glands in the marine file snake and the true sea snakes. Journal of Comparative Physiology, 227, 430-438.
- Dunson, W. A. & Dunson, M. K. (1979) A possible new salt gland in a marine homalopsid snake (Cerberus rynchops). Copeia, 1979, 661-672.
- Karns, D.R., A. O’Bannon, H.K. Voris, and L.A. Weigt. 2000. Biogeographical Implications of Mitochondrial DNA Variation in the Bockadam Snake (Cerberus rynchops, Serpentes: Homalopsinae) in Southeast Asia. Journal of Biogeography 27(2): 391-402.
- Murphy, J.C., H.K. Voris, and D.R. Karns. 2012. The dog-faced water snakes, a revision of the genus Cerberus Cuvier, (Squamata, Serpentes, Homalopsidae), with the description of a new species. Zootaxa 3484: 1-34.
- Voris, H.K. and J.C. Murphy. 2002. The prey and predators of homalopsine snakes. Journal of Natural History 36(13): 1621-1632.
Southeast India, Orissa State
Widely distributed in the Philippines.
This is a widely distributed species of snake, currently recognized to occur in Australia, New Guinea, Indonesia, Bangladesh, Cambodia, India, Malaysia, Myanmar, Singapore, Sri Lanka, Thailand, Vietnam, and the Philippine islands. In the Philippines this species occurs throughout most major faunal regions.
Distribution: Australia (North Territory, Queensland, West Australia), New Guinea, Indonesia (Ambon, Babi, Bacan = Batjan, Bali, Bangka, Borneo, Buru, Butung, Dolak, Enggano, Flores, Goram, Halmahera, Irian Jaya, Java, Kalimantan, Lombok, Mentawai Archipelago, Nako, Natuna Archipelago, Nias, Riau Archipelago, Roti, Sangihe Archipelago, Saparua, Seram, Simeulue, Sulawesi, Sula Archipelago, Sumatra, Sumba, Sumbawa, Talaud Archipelago, Ternate, Timor, We, Wetar, Komodo); Bangladesh; Cambodia; India (Gujarat etc.; including Andaman and Nicobar Islands); Malaysia (Malaya and East Malaysia, incl. Pulau Tioman); Burma (Myanmar); Philippine Islands (including Palawan, Panay, Luzon); Singapore; Sri Lanka; Thailand; Vietnam novaeguineae: Indonesia (Irian Jaya).
Type locality: “Ganjam” (Orissa State, SE India)
Habitat and Ecology
IUCN Red List Assessment
Red List Category
Red List Criteria
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)
- Boulenger, George A. 1890 The Fauna of British India, Including Ceylon and Burma. Reptilia and Batrachia. Taylor & Francis, London, xviii, 541 pp.
- Karns,D.R.; O'Bannon,A.; Voris,H.K. & Weigt,L.A. 2000 Biogeographical implications of mitochondrial DNA variation in the Bockadam snake (Cerberus rynchops, Serpentes, Homalopsinae) in Southeast Asia. J. Biogeography 27: 391–402
- Schneider, J. G. 1799 Historiae Amphibiorum narturalis et literariae. Fasciculus primus, continens Ranas. Calamitas, Bufones, Salamandras et Hydros. Jena, 266 S.