Cerberus rynchops belongs to the family Homalopsidae, which refers to Indo-Australian rear-fanged water snakes. It is considered one of the most widely distributed of the Homalopsidae, found occupying both Oriental and Australian regions from India to Wallacea. (Alfaro, et al., 2004; Brischoux, et al., 2012)
Bockadams live in near-shore coastal waters including marine, brackish, and freshwater environments. Their habitats are mostly mangrove forests, tidal mudflats, and estuarine areas. They will also travel on sandy beaches, but they spend the majority of their life in some type of water. Salt glands are what allow them to live in marine environments because they can expel salt through them in order to survive. Asian bockadams are the only homalopsid species known to have one, which makes them the most widespread Homalosid. However, their salt glands are less effective than other sea snakes and so they have a much more limited range compared to groups like the Hydrophiinae (coral reef snakes). Asian mud snakes also tend to avoid deep water, unlike other marine snakes. (Alfaro, et al., 2004; Brischoux, et al., 2012; Rahman, et al., 2014; Rasmussen, et al., 2011)
Asian bockadams are characterized by a wide head and snout, which is where the epithet "dog-faced water snake" comes from. They are striped and dark brown with a white underbelly. On both sides of their head, they have Duvernouy's glands which are the subject of ongoing debate and research. It's possible they are primitive venom glands which helps with swallowing and are mildly venomous. Cerberus rynchops is also opisthoglyphous, meaning they have an enlarged pair of teeth behind the maximille that point backwards. Most aquatic snakes, including bockadams, have more flattened tails and very small scales which allow them to swim better. (Alfaro, et al., 2004; Jayne, et al., 1988; Mori, 1998)
One unique adaptation of homalopsids is their valvular nostrils. Their glottis can extend to the internal nares, creating a water tight seal which allows them to live underwater without drinking or inhaling too much liquid. (Rahman, et al., 2014)
Dog-faced water snakes are one of the few viviparous snakes, so they are born live in water. (Alfaro, et al., 2004; Jayne, et al., 1988; Mori, 1998)
Asian bockadam mating systems remain largely a mystery, but they are likely comparable to sea snakes in northern Australia which mate in the winter. Males compete for females attention by chasing them through the water using fast zigzag movements. (Lynch, et al., 2021; Rasmussen, et al., 2011)
Not a lot is known about the reproduction process, however they are viviparous. (Mori, 1998; Rasmussen, et al., 2011)
Once young bockadams are born, they are independent from their parents. (Rasmussen, et al., 2011)
There is very little research on the lifespan of any Homalopsid snakes. However, the longevity of a comparable species (a coral reef snake) in captivity is 7 years.
Cerberus rynchops is a solitary species that spends most of it's time hunting fish and moving between different salt and freshwater areas. They generally stay within 50km of the shoreline in areas with warm annual temperatures and lower, but variable salinity. (Brischoux, et al., 2012; Rahman, et al., 2014)
Just like most snakes, bockadams do not see well, so they interact with their environment mostly based on smell and touch. Snakes use an organ in the roof of their mouths to identify chemicals around them. (Alfaro, et al., 2004)
Asian bockadams are piscvivorous and mostly ingest fish head first. This reduces any potential resistance from the prey's limbs and reduces swallowing time. While more generalist water snakes have been observed coming on land to swallow and digest, C. rynchops swallow their prey underwater. Their prey consists mostly of fish, but they have also been observed eating crustaceans, and frogs. The fish they eat includes gobies, apogonids, siganids, oxydercine gobies, catfish, mullet, and eels. While feeding, they will often anchor themselves or swim backwards in order to re-clamp the jaw around struggling prey. There's a period of prey holding before consumption which is assumed to be the time it takes for the venom to kill or immobilize prey. (Jayne, et al., 1988; Mori, 1998; Rahman, et al., 2014)
The two main anti-predator adaptations are camouflage and venom. Mud snakes adapted to blend into their habitat: mud. Their drawl brown, striped appearance helps them blend in with shallow, murky waters and mangrove forests. Venom is their second defense, they will bite and inject venom into something they perceive as a threat. (Rasmussen, et al., 2011; Voris and Murphy, 2002)
The main role of Cerberus rynchops is as a predator. They control fish and amphibian populations in salt marshes, mangroves, and estuaries. (Jayne, et al., 1988)
Bockadams are hunted as part of the international interest in reptile skin, organs, and meat, but they are also of special interest along with other aquatic snakes due to their venom.
They also serve vital ecosystem functions of controlling fish and amphibian populations. (Rasmussen, et al., 2011)
The main adverse effect on humans is harming them through venomous bites. Fishermen are the most common victims, especially when handling nets that have been trawled or dragged in muddy coastlines or estuaries. (Rasmussen, et al., 2011)
Dog-faced mud snakes are not legally endangered under CITES or any other international list. However, they are under unevaluated threat due to hunting, bycatch, and pollution. There are national and international laws impacting the trade of their skin, organs, and meat. (Rasmussen, et al., 2011)
Helen Jewart (author), Colorado State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
areas with salty water, usually in coastal marshes and estuaries.
an animal that mainly eats meat
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.
A substance that provides both nutrients and energy to a living thing.
mainly lives in water that is not salty.
the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
generally wanders from place to place, usually within a well-defined range.
found in the oriental region of the world. In other words, India and southeast Asia.
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
an animal that mainly eats fish
having more than one female as a mate at one time
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
young are relatively well-developed when born
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