According to the Carnegie Museum of Natural History, there are about 35,000 species of land snails in the world – and more yet to be traced and identified. In India alone, according to estimates, there are about 2,000-3,000 species of land snails.
In a way, they are considered pests as they severely damage young crops during the monsoons and have been known to serve as hosts for parasites such as roundworm (Angiostrongylus cantonensis). Aestivating during the summers and hibernating through the winters, Indian land snails are active only during the monsoons – reproducing only through late May to early August.
For decades, they had a balanced cycle of life – come out from their shells when it rains, find food, mate, produce offspring to replenish the snails that died or got eaten, and as soon as the soil begins to dry, go back to sleep.
But as climate change swept across the world in recent years, India was not spared – shorter and late monsoons, erratic patterns of rainfall, and most importantly, local droughts changed the whole biological landscape of the country. Even the Western Ghats, one of the most active biological hot-spots in the world, a UNESCO World Heritage Site and the home of thousands of endemic and rare species of wildlife, did not remain unaffected. And although the rainforests helped preserve most of the endemic fauna, snails didn’t have the odds in their favour.
Coming out from aestivation only when it is moist outside, Indian snails have grown accustomed to their waking patterns, as in the past rainfall in India seldom differed. But nowadays, after only a shower or two, just as all the snails have begun to be active, the rain stops abruptly, only to restart weeks later. What happens to the snails during those days? Most of them die, left exposed to the severe heat and dryness that India is renowned for. Only a few which manage to either locate another source of water or not wake from aestivation are left as the only survivors.
What people need to understand today is that human activities are not only destroying the habitats of large wildlife such as tigers and panthers, but also endangering the sustenance of smaller, and often overlooked molluscs. Farmers complain of snails raiding their crops but where else could they possibly go, since there are no untouched fields and forests left anymore?
Pollution as well as global warming has contributed largely to the nuisance caused by snails nowadays. Nature ensures that the ecological balance is maintained in all situations – snails have many predators that should ideally keep their population in check. And the mere knowledge that these molluscs are running rampant over some areas, while other areas are completely deficient is a testimony to the fact that ecosystems are falling apart.
Much of India’s fauna depends upon snails as a source of food – firefly larvae, frogs, toads, rodents, salamanders, snakes and most importantly, birds. After all, parrots and parakeets require lots of calcium in their diet, and in the wild, there is nothing richer in calcium than snail shells.
So, even though we might turn and look the other way when someone mentions the decreasing populations of certain land snails, the repercussions can be fatal. If all Indian land snails disappear, not only will a large sector of the food chain be disrupted, but humans will suffer too. India is still a home to many undisturbed indigenous tribes, and snails constitute a major part of their diet.
Moreover, as if the threat posed by erratic rainfall isn’t deadly enough, modernization has brought even more problems – Indian highways and other blacktop roads are another threat to the dwindling snail population. Certain species such as Macrochlamys indica tend to ‘migrate’ in groups towards greener pastures or a year-round source of water. While doing so, they cross many busy roads – roads with traffic that never stops for anyone.
Saying dozens if not hundreds of snails getting trampled by vehicles every monsoon as simply ‘survival of the fittest’ is very disgraceful. The occasional death or two by maybe getting crushed under an elephant foot would be more of a natural selection.
Simply because snails aren’t as unique and interesting as say, a peacock, should not be the reason that they are being killed unnecessarily. Even mosquitoes are pests – they bring malaria or dengue. But eradicating even them would be wrong – they also have a part in the food chain. It’s time we realised that the overpopulation or rampage of snails in an area is not their fault – we give them lesser green areas to live in and then plant crops in their home. Where are they supposed to go?
Personal experiments and observations
For seven years, I have observed and researched Indian land snails in captivity – especially Macrochlamys indica, Glessula sp. and Subulina octona on the edge of the teeming Western Ghats. Collecting specimens from the same areas every monsoon, I have noticed a rapid dwindling in their numbers – especially around the last two years. And it wasn’t that they had migrated elsewhere – dead and empty shells were commoner than ever.
In my experience, while breeding Macrochlamys indica, I have noticed that adults tend to lay more clutches of eggs when subjected to erratic rainfall patterns and the hatched snails tended to be weaker and less adaptable to harsh climatic conditions. Whereas, when subjected to regular watering, the adults grew healthier, laid lesser eggs and the hatchlings were of superior quality. While considering an infestation of these snails over any area, I think these are some of the factors to be considered, rather than just eliminating them.
Also, adult Subulina octona, a roundworm host, seemed to prefer being left in the wild and eating mulch rather than infesting crops and damaging the plants. Glessula sp., however, has adapted itself to eat man-made products and it is not uncommon to see adults thriving on nothing but moist paper and cardboards.
As the years progress and rainfall gets more and more difficult to predict, not only has collecting live specimens become more difficult, but many unidentified species have almost become extinct without ever being officially discovered.
This is a guest post written by Prapti Panda.
Prapti Panda is a sixteen-year-old author and nature photographer. Her passion for conservation sparked off 8 years ago and since then, she has devoted herself towards documenting the ecology of rare flora and fauna. When not conducting specific research projects, Prapti serves as an active member on Project Noah.