Face Off With The Dog-Faced

The Dog – faced snake (Cerberus rynchops),, is a mildly venomous species belonging to the Homalopsidae family.

It is known by a number of names as the New Guinea bockadam, South Asian bockadam, bockadam snake, or dog-faced water snake. It is perfectly suited for the wet, muddy Sundarban habitat. The nostrils of this species are higher up on the slightly upturned snouts – it is this feature that gives this species its name.It is midlly venomous and has fangs on its rear.This is an aquatic and nocturnal species , mainly feeding on fish.

Let us take a closer look :

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Range – The dog – faced water snake is con­sid­ered one of the most widely dis­trib­uted of the Homa­lop­si­dae family , found across south east Asia to Australia, from India to Wal­lacea.

It is native to coastal waters of South and Southeast Asia.India, Bangladesh, Myanmar, Thailand and Malaysia host significant numbers. In 2012, this species was re-delimited, allocating populations east and south of the Thai west coast to other species.

The eastern limit of its distribution with Cerberus schneiderii is uncertain.

Habitat – It is found in tropical saltwater or marine freshwater, commonly in mangroves, mudflats, estuaries, streams, ponds, tidal pools, on algae patches, and is often found burrowing into the mud.

Appearance – This species is ectothermic ( cold- blooded )and posseses bilateral symmetry( body can be divided into two equal halves when placed on a plane ) . Medium in size, it is usually between 60 – 80cm , although some grow to be bigger than 100 cm.Newborns are about 15-25 cm. The average mass is about 105 grams.The distinctive upper jaw is visible, which gives it a dog-like appearance. The head is long and distinct.The Du­vernouy’s glands, located on the two sides of the head , is a sub­ject of on­go­ing de­bate and re­search. It’s pos­si­ble they are prim­i­tive venom glands which help capture of prey and swal­low­ing food.

The dark gray dorsum ( back ) has faint, dark blotches and a dark line along the two sides of the head, across the eyes.The central part is creamy with two large, diffused dark gray spots arranged in rows.This species is striped and dark brown and also has a white un­der­belly.

The eyes are small and beady and have rounded pupils. The scales are distinctly keeled, with 21–25 scale rows in the middle, 132–160 in the ventral ( abdomen ) and 49–72 in the subcaudals ( underside of tail).

Sexual dimorphism is evident, with females being larger than males.

Characteristics – Cer­berus ryn­chops is also opistho­glyp­hous, mean­ing they have an en­larged pair of teeth be­hind the max­illa ( bony,.plate like structure of upper jaw ) that point back­wards. Most aquatic snakes, in­clud­ing bock­adams, have more flat­tened tails and very small scales which allow them to swim bet­ter.

Salt glands below the upper lip discard excess salt acquired from the brackish water they consume.This is an excellent adaptation they have to survive in marine environments.How­ever, the salt glands of this species is less ef­fec­tive than other sea snakes.

One unique adap­ta­tion of Homa­lop­sids, which this species posseses, are valvu­lar nos­trils. The glot­tis ( tube like opening at the bottom of the mouth which connects to the trachea ) ex­tend to the in­ter­nal nares ( paired openings in the roof of the oral cavity connecting the nasal cavity to the pharynx) , cre­at­ing a watertight seal which al­lows them to live un­der­wa­ter with­out taking in too much liq­uid.

Com­mu­ni­ca­tion and Per­cep­tion – Like most snakes, bock­adams have poor eyesight and mostly in­ter­act with their en­vi­ron­ment based on their senses of smell and touch. It uses the Jacobson’s organ in the roof of their mouths to iden­tify chem­i­cals in surroundings.

Diet – The dog – faced’s prey con­sists mostly of fish, but it also has a taste for crustaceans, frogs and also arthropods. The fish mostly eaten in­cludes go­b­ies, apogo­nids, siganids, oxy­dercine go­b­ies, cat­fish, mul­let, and eels.

This pis­c­viv­o­rous species mostly in­gests fish head first to re­duce any po­ten­tial re­sis­tance from the prey’s limbs and also to re­duce swal­low­ing time.C. ryn­chops swal­lows its prey un­der­wa­ter.While feed­ing, it often an­chors itself or swims back­wards in order to strengthen its grip over strug­gling prey and release the venom which is enough to kill or immobilise it.

Reproduction – The mating system of the dog – faced snake is polygynous, with males mating with multiple females. Iteroparous or seasonal breeding is the norm,.with winters marking a period of heightened activity.Homalopsid snakes such as the dog – faced are thought to breed every two years.The sexes are distinctly separate, that is they are dioecious.The average number of offsprings are five, although the offspring range could be anything between two to forty.

Males com­pete for fe­males at­ten­tion by chas­ing them through the water following fast zigzag move­ments.Interestingly, dog-faced water snakes are one of the few vi­vip­a­rous snakes, so they are born in water. Once young bock­adams are born, they are in­de­pen­dent from their par­ents.

Lifes­pan/Longevity – There is very lit­tle re­search on the lifes­pan of any of the Homa­lop­sid snakes. How­ever, the longevity of com­pa­ra­ble species such as coral reef snakes in cap­tiv­ity is 7 years.

Threats – Other than humans, main threats to the dog – faced include the tiger shark (Caracharhinus caustus), pariah kite (Milyus migrans), and the very commonplace mangrove crabs (Scylla serrata),

The two main anti-preda­tor adap­ta­tions of this species include cam­ou­flage and venom. Mud snakes are adapted to blend seamlessly into their habi­tat: mud. The brown, striped ap­pear­ance helps it blend in with shal­low, turgid wa­ters in man­grove forests like Sundarban.Siimilarly, with any threat perception , a bite and injection of the venom is part of its defence mechanism.

Ecosys­tem Roles – The main role of Cer­berus ryn­chops is that as a preda­tor, con­trolling fish and am­phib­ian pop­u­la­tions in salt marshes, man­groves, and es­tu­ar­ies.

Sometimes hunted as part of the illicit in­ter­na­tional market in snake skin, or­gans and meat.Extraction of venom also elicits human interest.

Dog – faced in Sundarban – It is most often spotted in water, as it happens to spend the majority of its time in water.The best bet to get this species would be the Sanctuary zone , both in the forest as well as on mudflats at the edge of large rivers.It is also spotted in sandy and muddy beaches to the south.This is a soli­tary species that spends most of its time hunt­ing fish and mov­ing be­tween salt water, brackish water and fresh­ wa­ter areas.It gen­er­ally stays within 50km of the shore­line in warm, tropical areas with vari­able salin­ity levels.

Con­ser­va­tion Sta­tus – It is not an endangered species, occupying the IUCN Red List.

How­ever, they face the regular threats of hunt­ing, by­catch, and pol­lu­tion.Trade of skin, organs and meat is strictly prohibited and bound by national and international laws.

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* This frame.comes in from Manoj Mondal , a friend of the mangroves.He has a deep connect with Sundarban ‘s wildlife and humans, and has been bringing the forest in intimate contact with tourists and outsiders for many years.