Get to know our Creepy-Crawlies: Snakes Around Us
Uttam Saikia, Asem Bipin Meetei and Abhijit Das write about this misunderstood species.
Normally the sight of a snake creeping around us evokes a sense of fear or revulsion. People consider snakes as dangerous creatures and this fear often promotes us to eliminate snakes that we see in our vicinity. There is certainly some truth in this perception, a comprehensive recent study pointed out that 1.2 million deaths occurred in India because of snakebite during the period of 2000 to 2019. This means, on average, a staggering 58 thousand people die each year in India because of snakebites. Although this huge number is a serious public health issue, we should not fret over it and go on a rampage eliminating all snakes in our neighbourhood. The objective of the present article is to put the snakes in scientific light and to dispel all-pervading fear of snakes existing among the common people.
Snakes are a significant component of biodiversity with over 3800 species worldwide; over 350 species are known from India. They are found all over the world (except for Antarctica and some oceanic islands like Ireland, Iceland, Greenland, among others), in all sorts of aquatic, terrestrial and arboreal habitats and from the sea levels up to the lofty heights of the mountains. In the state of Meghalaya, well over 50 species of snakes are known, some of which are very common to a few extremely rare species. For example, the Indo-Chinese rat snake, a relatively large but innocuous snake is very common throughout the state while another snake called Khasi Earth Snake discovered from Khasi Hills in 1870 was never to be seen again.
Snakes play an important role in maintaining the balance of food chain. Most snakes are predators of frogs, lizards and rodents and help keep their population under check. This is especially important for rodents. many of whom are serious agricultural pests. The abundance of ectoparasites also decrease, some of which are vectors for human disease. Snakes also serve as a prey item for a number of birds, mammals and even snakes. You will be surprised to know that the King Cobra exclusively feed on snakes. Everything is so intricately intertwined in the ecosystem that severe decline in any of these components (including snakes) could have a catastrophic effect on the overall health of ecosystem and consequently, human health.
For the sake of convenience, we can loosely divide snakes in to two groups: venomous and non-venomous. Although, for a layman, it might be difficult to distinguish these two groups of snakes at first sight; a few site-specific superficial characters might help. Night active shiny black snake or green snake with almost triangular shaped head should be treated as a dangerously venomous black krait or pit Vipers respectively. On the contrary, majority of the snakes of Meghalaya having long stripes on their back are non-venomous.
Venom evolved in snakes primarily to kill or immobilize its prey and to aid digestion; however, it can be used for self-defence when threatened. Fortunately, a large majority of the snakes we see around us are non-venomous, meaning there is no existential threat from them! In fact, about 70 species of snakes in India do possess venom glands and a mechanism to deliver it to the prey (fangs). However, this includes about 20 species of sea snakes and many forest species that we do not come across often and therefore, do not constitute a significant human health hazard. Some of the venomous snakes of significance in Meghalaya include King Cobra, Monocled Cobra, Black Krait, Mountain Pit Viper and a few species of Green Pit Vipers. King Cobra is the longest venomous snake in the world attaining an average length of three to four meters and can be easily distinguished by its large size and whitish bands over the glossy black body. It is an uncommon snake and normally inhabits forested areas. We obtained recent photographic evidence of its presence in Mawryngkeng area in the vicinity of Shillong city. Monocled cobra is of more common occurrence in Meghalaya especially in the lower altitude areas. Although superficially resembles to a harmless rat snake, it has got a distinctive ‘O’ pattern in the hood and an olive brown or blackish body. It is quite adapted to anthropogenic areas and can be found in human periphery, in paddy fields, where rats, lizards, frogs are plentiful. Because of its potent neurotoxic venom and ‘ready to strike’ nature, it is one of the most medically important snakes in north-eastern India and could be responsible for many snakebite deaths in the region. Mountain pit viper is a common snake in the region of NE India. A medium sized snake, it is relatively easily identified by its brick brown body with black blotches and triangular head. Although not much is known about its venom toxicity, there has been a recent report of death from bite of this snake in Meghalaya. There are a few species of kraits in Meghalaya and they are known for their potent neurotoxic venom. The Black kraits in lower reaches of Meghalaya are one of the dangerously venomous species. They are shiny black and night active snakes. Himalayan Krait, a rare cousin of the former can be identified by black body with narrow white bands on the head and body. Fortunately, although very venomous, most of the kraits are gentle in nature and unwilling to bite unless disturbed repeatedly. The green pit vipers are a group of arboreal snakes characterized by short, stout and green body. They remain camouflaged among vegetation, often close to streams and are active at night. Pit Vipers venoms are largely hemotoxic in nature and can damage vascular system.
Many of the most common and abundant snakes in Meghalaya are non-venomous and include Rat snake, Trinket snake, Wolf snake, Keelback water snake, to name a few. Large growing harmless rat snakes can be easily distinguished from venomous cobra by observing their fish scale like black and white bars on the side of its mouth and a narrow head shape. Trinket snakes can be distinguished by long stripes on their body.
The hazard of snakebite and mitigation: There is no denying the fact that snakebite is a major human health hazard in rural India. However, we must remember that snakebite is an accident and we can actually effectively avoid it. It is important to stress that not all snakebites are fatal as they may involve non venomous snakes or envenomation (actual delivery of venom) may not have occurred. Only a handful of snakes are responsible for an overwhelming percentage of these deaths. These snakes are classified as ‘big four’ and include Indian Cobra, Common Krait, Russell’s Viper and Saw Scaled Viper. Fortunately for Meghalaya, none of these four dangerous snakes occur in the state, but replaced by some other venomous snakes, mentioned earlier. A recent bi-decadal study on the snake bite deaths in India found that the absolute risk of death from snake bite is the lowest in the NE India. Researchers have established that most of the snakebites in India happen in the plains during the monsoon season and in outdoor environment. Further, the bite site mostly involves the lower extremities i.e., toes and feet. This happens when someone accidently steps over a snake. Therefore, while venturing out especially in the dark, it is very important to wear shoes and carry torchlight. In the hot areas during summer, people often sleep in the ground which should be avoided. Also, keeping one’s surroundings clean and tidy helps at both reducing infestation of prey, rendering it unattractive for snakes.
Remember, treatment with modern anti venom in a hospital setup is the only proven remedy for envenomation. Although there are issues with effectiveness of current anti-venoms in use, timely intervention by a qualified physician can certainly help save life. And for the sake of conserving these beautiful creatures, we are better off trying to avoid them rather than indiscriminate killing.
Author affiliations: The authors (first two) are scientists at Zoological Survey of India, Shillong and (last) Wildlife Institute of India, Dehradun.
Photo copyright: Authors