The Skin of Many Colours: Morphs of the Malabar Pit Viper

Why it’s not easy to identify this snake species and the mystery of its diverse and changing colours

By Roundglass Staff

Malabar pit vipers are a fascinating species. For one, they are endemic to the Western Ghats, which means they aren’t found anywhere else on the planet. Secondly, the young develop inside the mother’s body and are born live, unlike most reptiles that hatch from eggs. This way of reproduction is called viviparity; it is also the reason this order of snakes is called vipers. But the most intriguing characteristic of Malabar pit vipers is their colour morphology, or their ability to change colour over the course of their life.

A number of species exhibit this ability. For instance, chameleons and cuttlefish can change their colours and patterns within a matter of seconds, and use this ability to confuse predators and blend into their surroundings. These changes are rapid and reversible. Species like dragonflies and deer deepen in colour around breeding season, presumably to attract a mate. These changes are more gradual. Others like the west African frog, develop colour when they attain sexual maturity, an indicator that they are ready to mate.

Malabar pit vipers are slightly different. Like many species of snake, they are born small, brown, and sometimes mottled, but at some point in their life, they begin to develop patterns and colour, ranging from green and blue, to brown and yellow, even vivid red and purple. These colourations vary dramatically within the species, making the snake hard to identify for laypersons.

Professional herpetologists like Gerry Martin look for other cues, such as the triangular shaped head and the heat-sensing pit organs, typical of MPVs. “We know they are one species because of genetic analysis studies,” he says. “Plus we have reports of differently coloured snakes mating together”, which is unlikely if they belong to different species.

Gerry is a researcher, conservationist, and spirited educator, who runs a snake research centre in Honsur, Karnataka. He conducts programmes that introduce children to snakes, and believes that education and a reconnection with nature are critical to conservation. Recently, Gerry received permission from the state forest department to start a research-breeding programme at his centre, where he will study the Malabar pit viper, in addition to cobras, Russell’s vipers, and other venomous snakes. “Right now,” he says, “there’s more we don’t know about them.”

Among the many things we don’t know about the Malabar pit viper is its life span. Gerry estimates it’s about 14-15 years, but it’s hard to say without a study. This makes it hard to establish a link between age and colour morphology. We don’t know if the colour changes are permanent or whether they change seasonally, or every few years. Most significantly, we do not know what prompts this alteration. What makes a brown-beige juvenile morph into a pale blue snake with deep coral markings along its body? Photo: Nirmal Kulkarni
Malabar pit vipers aka Trimeresurus Malabaricus, belong to the Viperidae family of snakes. There are over 30 species of vipers in India, and researchers estimate there are numerous more, yet to be classified. This image was taken in Agumbe, Karnataka. Cover Photo: Anuroop Krishnan

One theory is that the colouration is a form of camouflage. This makes sense when one considers the behaviour pattern of the Malabar pit viper. They are known to have a small home range, and spend their days coiled up around a branch, or sunning on a rock. At night they hunt prey such as rodents and smaller reptiles. “Within their micro-habitat, like the kind of laterite rock found in Goa, a yellow or crimson snake would be nearly indistinguishable from its background,” Gerry explains. “Out of their element however, they are striking.” Photo: MV Shreeram

Some researcher’s believe that the snake’s morph is a good indicator of its habitat. “Most large MPV females are green with chocolatey mottled colours,” Gerry says. “When viewed from above, these colours break the form of the animal, making it very difficult to distinguish them from a branch covered with moss or lichen.” Photo: Pradeep Hegde

Another theory is that the patterns and colours are meant to confuse predators. Since Malabar pit vipers look so diverse, natural predators like cobras and monitor lizards might find it harder to identify their meal of choice. Photo: Pradeep Hegde

Still other researchers have theorised that the viper’s vivid morphs might be helpful with aerial predators, such as eagles. Viewed from above, these patterns make the snake harder to follow in a chase. Photo: Nirmal Kulkarni

Instead of colour, herpetologists recognise the species by its triangular head, body shape, and the presence of pit organs on either side of the nose. Photo: Varadbansod – CC BY-SA 4.0

The next step in identification is to count the number of scales on the snake’s body. Every species has a certain arrangement of scales, so noting the number of scales along the dorsal and ventral side, is a good way to ID species. Photo: Nirmal Kulkarni

Male and female vipers vary slightly. Males are generally smaller, and slimmer than females. Based on anecdotal evidence and observations, Gerry says males appear to have duller, more mottled morphs, and are seen on ground level. Females however, prefer spending time up in the canopy, and display more vivid morphs. Their choice of micro-habitat makes them more vulnerable to deforestation, and their numbers are hard to estimate. Photo: Dhritiman Mukherjee

Newborn MPVs moult every 10-15 days in the first few months of their lives. First, their eyes go milky, then their outer skin begins to separate from their bodies, and finally, they exude a lubricant to ease exit from the former shell. This process takes several hours, and appears to require high amounts of energy. As adults, Gerry says, MPVs generally shed their skin after a large feed. “The eyes go milky, because the eyes are a type of scale. When they moult, the old eye scale pops out, like goggles.” There is no known connection between the snake’s moulting and colour morphology. Photo: Pradeep Hegde

Of late a drop in the numbers of Malabar pit vipers has been noticed and sported. In addition to human threats (many snake encounters end in the death of the reptile), the species also faces habitat loss and death due to industrialised farming practices such as pesticide use. Photo: Pradeep Hegde

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