Found in a variety of waterbodies, from streams and swamps to water-logged agricultural fields and the intertidal zone, aquatic snakes have a great affinity for water
Text by: Sustain Team
Found in a variety of waterbodies, from streams and swamps to water-logged agricultural fields and the intertidal zone, aquatic snakes have a great affinity for water
When we think of snake habitats, most of us think of forests with moss-covered trees and gently decomposing leaf litter. Or desert sand dunes, shimmering in the sun, etched with serpentine markings. However, snakes are found in all manner of habitats, from the high mountains to the ocean, even in cities as large as Delhi, Bengaluru, and Mumbai. According to National Geographic, “There are more than 3,000 species of snakes on the planet and they’re found everywhere except in Antarctica, Iceland, Ireland, Greenland, and New Zealand”.
Amidst this diversity of serpents are water snakes: a subcategory of snakes that have an affinity for water or spend a significant amount of time linked to water-based habitats. “All snakes can swim,” explains herpetologist-conservationist Nirmal Kulkarni, who lives and works in the Chorla Ghats of Goa. “In fact, all snakes are good swimmers, and have to drink water in order to survive. Water snakes are a common grouping of snakes that are found in the vicinity of waterbodies.”
Some species, such as the rainbow water snake (Enhydris enhydris) and dog-faced water snake (Cerberus rynchops) are found in estuarine habitats such as mangrove forests. Snakes in the genus Rhabdops, including Rhabdops olivaceus and the Rhabdops aquaticus, inhabit streams in the Western Ghats, while Siebold’s water snake (Enhydris sieboldii) is found in and around rivers in central India.
Water snake is not a taxonomic classification and the category does not include sea snakes, those found in oceans. Sea snakes have distinct physiological features, such as rudder-shaped tails, that help them navigate their marine habitat. Many species of sea snakes are uncomfortable on land. In general, water snakes are linked to aquatic habitats, for hunting prey, refuge, or in other ways important to their survival. They are usually found close to waterbodies, but they are also comfortable traversing terrestrial habitats. They have physical characteristics that allow easy movement in water. Most water snakes have eyes and nostrils located towards the top of the head, allowing them to see and breathe with only the tip of the head above water. Like many areas of herpetology in India and worldwide, research on water snakes is limited.
Many aquatic snakes are found in intertidal zones, where freshwater and marine habitats overlap. Among these is the glossy marsh snake that inhabits creeks along the coast. “Long back, when I used to actively rescue snakes in Mumbai, we’d often see this snake around Gorai creek,” recalls Kedar Bhide, a biologist and wildlife photographer with an interest in snake conservation. “They would be seen near the mouth of irrigation canals around the time water would be released. They used the channels to travel from place to place. Very beautiful, and very intelligent creatures.” The glossy marsh snake (Gerarda prevostiana), cat-eyed water snake or Gerard’s water snake, is found in estuarine habitats across Asia. It survives on a diet of fish, small crabs, and mudskippers. Photo: Achyuthan N Srikanthan Cover photo: The checkered keelback is among the most commonly seen aquatic snake species in India, with a wide range across the country. Photo: Saurabh Sawant
The checkered keelback (Fowlea piscator) is a freshwater species seen in both urban and rural settings, in ponds, storm drains, canals, temple water tanks, even fountains in gardens. “The checkered keelback is like the friendly neighbourhood snake,” says Kulkarni. “It is among the most accepted of snake species, often seen in small lakes, and farms where they keep rat populations in check.” It is protected by the Indian Wildlife Act of 1972, as the snake was once widely poached in the snakeskin trade because of its beautiful markings. Photo: Vipul Ramanuj
Checkered keelbacks are found across India, from the Himalayas to the plains of Kerala and the forests of Northeast India — in freshwater habitats. They are active during the day and night, have voracious appetites, and a varied diet that includes frogs, rodents, fish, and crabs. “In Mumbai, I have even observed these snakes eating waste from fish markets,” says Bhide. Photo: Shreeram MV
The olive keelback (Atretium schistosum) is also a freshwater snake that is non-venomous. Some of them have red lines running longitudinally along their bodies. Researchers have reported seeing this snake in peninsular India particularly, Tamil Nadu, Karnataka, and Andhra Pradesh, but also in Uttar Pradesh and Odisha. It is seen in paddy fields, swamps, in and near waterbodies, and feeds on fish, frogs, and toads. Photo: Ajay Kartik
The rainbow water snake (Enhydris enhydris) goes by many names, including common smooth-scaled water snake and striped water snake. It is found in mangrove habitats with brackish water and “has a body that feels extraordinarily smooth, bordering on slimy, like a caecilian,” says Kulkarni. “They can be seen around low tide, eating fish and smaller crabs, though sighting them often involves wading through knee-deep muck in the mangrove marshes.” Like many water snakes, this species is characterised by eyes located towards the top of the head. Photo: Srikaanth Sekar / CC BY 2.0
Kulkarni describes the dog-faced water snake (Cerberus rynchops) as a “…very unusual looking species, with a jaw that looks almost dislocated”. It is found in mangrove habitats like Coringa National Park, Andhra Pradesh (where this image was taken). Dog-faced water snakes are nocturnal, swift swimmers, and prey on fish and other aquatic animals found in marshy areas. Kulkarni says, “they were in great demand with snake charmers about 20 years ago, because they looked so different”. Photo: Dhritiman Mukherjee
Dog-faced water snakes exhibit fascinating behaviour. “There has been a lot of talk of them practicing male combat,” says Kulkarni, where male snakes battle each other, by head-butting and wrestling, for mating rights. “No biting though. At some point, one of the snakes simply backs off, and the other one mates with the female.” Until proper research is conducted however, these traits remain anecdotal evidence. Photo: Achyuthan N Srikanthan
The file snake (Acrochordus granulatus) is another resident of the inter-tidal zone, “named after its scales, which are very rough, like a file” says Varad Giri, a taxonomist and herpetologist with a keen interest in snakes and amphibians. “Interestingly, the nostrils of the file snake have a muscular kind of septum, like a plug, that comes up when they go underwater, sealing their nostrils and keeping the water out. This is a feature that many aquatic snakes have, and one of the things that make them so interesting.” File snakes are found close to the mouth of rivers. They spend most of their time in the water, and amidst mangrove mud swamps. Photo: Achyuthan N Srikanthan
Far from the marshes of the coast, Rhabdops aquaticus inhabits the rocky plateaus of the Western Ghats, and is the “typical aquatic snake of this habitat,” says Varad Giri. The Rhabdops genus has two species: olivaceus and aquaticus, both of which are aquatic snakes that are endemic to the Western Ghats. Rhabdops aquaticus is found widely in the Northern Western Ghats, in Maharashtra, Goa, and Karnataka, according to Giri. He says, “In some areas, I have counted 80-90 individuals in a stretch of about 500 m”. Juveniles are olive green in colour, possibly because they inhabit water logged areas with vegetation, while adults have a brown dorsum, which camouflages them in rocky streams. “I have seen the aquaticus remain under water for 45 to 47 minutes,” Giri says, adding that they are “very docile”, and have the distinction of “flicking their tongues underwater”. Photo: Dhritiman Mukherjee
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Sustain Team
We are a driven group of people from diverse backgrounds, bound by an abiding love for India’s natural world.
