Caves have always captured the human imagination. Dark, mysterious, and inhospitable they have been a place of exploration and worship. Often seen as a gateway to the spiritual world and a place to unlock earth’s timeless mysteries, cultures have often believed caves to be both sacred religious sites and ecological wonders. Accordingly, it is no surprise that Malaysia’s most important site of Hindu pilgrimage and the world’s most researched cave is the Batu caves just outside Kuala Lumpur. Here a 43m golden statue of Lord Murugan, the largest in the world, guards the entrance to the caverns and solemnly gazes out at the distant city skyline. After sweating and panting up 272 steps, Hindu devotees and tourists alike find what little breath they have left taken away by the spectacular chambers before them. The shrine cave, lit primarily by rays of sun shining through natural skylights hundreds of feet above, features several shrines which every year in January or February see the arrival of over a million Hindu pilgrims from across Southeast Asia for the festival of Thaipusam. The temple originated in 1890 when the Indian trader k. Thamboosami lillia became inspired by tthe cavern’s spear (vel) shaped entrance. The Dark Cave, 20 meters to the West, has become a place of pilgrimage for scientists seeking to uncover the secrets of its unique geological and ecological diversity. Here is home to pure darkness, precious stone and earth’s rarest spider.
Geologically the caves began forming 440 million years ago when this region was an ocean bed. Sediment and dead sea life compressed to form limestone and 220 million years later this limestone was thrust upward as colliding tectonic places formed the Malaysian Peninsula. The cave itself, the primary formation, was formed through the eroding powers of a rushing underground river 120 million years ago. After the river dried or was redirected, the Batu caves secondary formations have been molded by the incremental dripping of groundwater through cracks, skylights, and fissures in the cave’s ceiling and walls. These trickles of water, acidified by the limestone, leave behind miniscule calcium deposits which comprise the shining stalactites, stalagmites, flow stacks, and cave curtains that over the ions will eventually seal the caverns shut. Secondary formations are incredibly slow processes – a single inch takes approximately a century to grow. All these smooth flowing formations hanging precariously from the ceiling and spiraling from the floor- their wet crystalline surfaces glistening like jewels under our torchlight- endow the caverns with a surreal, other-worldly nature which makes it no wonder that humans have granted them a mythical sacred status.
Nearly every aspect of the caves seems inhospitable to life. The water is highly acidic and the absence of sunlight envelopes all but a very few sections of the cave. However, the Batu caves are quite literally crawling with life. Over 200 animal species, many of which are endemic, thrive in this harsh, unforgiving environment. With the exception of several recently discovered organisms in the deepest regions of the ocean, all of the world’s species derive their energy either directly or indirectly from the sun and cave dwellers are no exception. For the species that never leave the darkness of the Batu Caves, the life-giving powers of sunlight are delivered to them by the cave’s largest mammals, its bats. Two species of bats, one a frugivore and the other a carnivore, exit the cave each night in search of food. The frugivore, relying on its enormous eyes to see in the dark, feeds on fruit thus indirectly receiving sustenance from the trees photosynthesis of light. The carnivorous bats, which are blind, use what is essentially a sonar system imbedded in their large ears to hunt insects. When these two species of bats, believed to number over a quarter of a million, return to the Batu Caves before dawn to escape the sun and rest, they defecate nutrient rich and pleasantly decptive named guano onto the cavern floors below.
The caves are carpeted thickly in pungent smelling guano. Give the guano a closer look and you’ll see that it is alive with the movement of thousands of insects. Over 150 species of invertebrates feed either on the guano or each other. Each has adapted an impressive array of characteristics that enable them to cope with the total darkness. One example is the spiny millipede. Capable of growing several inches in length, its awkward looking legs grow far longer than those of its surface relatives, acting akin to a blind man’s cane alerting them of obstacles and movement ahead. The caves’ snails, which cling to the stalactites and stalagmites, develop their strong protective shells by absorbing calcium carbonate from the formations and the water dripping down them. While the commonly held belief that worms can be cut in half and continue to survive is largely a myth, the Batu cave’s flatworms really are capable of regenerating themselves, making the worms of particular interest to cancer researchers. There are many species of spiders that inhabit the caves as well. Some blindly construct messy looking webs which they patrol by detecting the vibrations of their prey. However the caves’ rarest occupant, the Batu variety of a trapdoor spider, doesn’t rely on a web at all. Instead, it builds a nest inside a pile of guano. Outside the nest’s main entrance it lays a tripline. Should some unsuspecting insect pass over the line, the trapdoor spider will feel the vibration and scurry out to gobble up its meal. If it happens to detect a much stronger vibration, the spider will be alerted to the dangers of an approaching predator and safely flee out of an escape door in the rear of its nest. Unchanged since the Jurassic period, the trapdoor spider’s genetic material could hold a wealth of scientific and medical possibilities.
Not all of the Batu Cave’s predators are small invertebrates. Slithering through the dark, cave racer snakes, growing as long as eight feet, stalk rats. They climb to the cavern ceiling and wait with open mouths for an unlucky bat to fly into their awaiting jaws. The caves’ largest predator and most recent arrival is a dog known only as girl. She is the third generation of dogs to live in the cave, but the first to spend all of her time there. Proving the ability of life to adapt to almost any situation, girl has not gone out into the light in over five years. The cave’s staff began feeding her when they realized she had learned to hunt bats. They removed her litter of puppies when, after several weeks in the cave, they did not opened their eyes. The staff was concerned that a new variety of blind cave dog would upset the balance of the delicate ecosystem.
The history of human interaction within the cave has been one of folly and discovery, piety and greed. The caves were first discovered by Chinese farmers in 1816. They used the guano inside to fertilize their fields. Prior to the advent of chemical fertilizers, guano provided some of the most effective means of fertilizing crops (today organic farmers have returned to using guano, though its sustainability is questionable). This made guano a highly lucrative commodity in the late nineteenth century. In the 1950’s, enterprising politicians in the expanding metropolis of Kuala Lumpur saw the possibility of tourist dollars and opened the dark caves to the public. Over the next forty years of unsupervised exploitation all but the least accessible recesses of the caverns would fall victim to desecration and pilfering. Pieces of stalactite which took centuries to form were quickly reduced to cheap souvenirs and visitors scrawled their names across the ancient cavern walls.
After pressure from scientists and NGO’s, the Malaysian government finally agreed to hand over control of the cave to the Cave Management Group who has worked tirelessly to restore the natural ecosystem, foster academic study, and advocate for the protection of similar cave systems across Malaysia. The Cave Management Group, which receives no government funding, supports protection of the cave through closely supervised and highly informative guided tours. These tours only venture through one third of the dark cave system. Another third is restricted to scientific research only, while the deepest remaining section home to the trapdoor spiders is closed to human contact.
Unfortunately the majority of Malaysia’s limestone caves are being systematically destroyed for their marble reserves. While Malaysia has vast marble deposits in caves which are sealed from the surface and therefore lifeless, mining efforts concentrate almost solely on the ecologically diverse surface mines which can be exploited much more affordably. If you happen to be in the market for marble we recommend as always doing consumer research to see from where and by what means your materials are being sourced.
Though the loss of these ecosystems may seem a rather insignificant cost to provide the world with relatively inexpensive stone countertops and a slight increase Malaysia’s GDP, the sharp decline in the bat population will have very noticeable consequences for Malaysia’s human population. The fruit eating bats are the primary pollinators of durian and other fruiting trees. Without them, a staple of the Malaysian diet may disappear. The insect eating bats, able to consume up to half their body weight in a single night are essential to controlling the mosquito population, thereby reducing the spread of Malaria and other life-threatening insect borne diseases.
To add insult to injury, the Malaysian government recently moved forward with granting developers approval to construct two twenty-three story condominiums directly in front of the Batu caves. This construction will not only block the view of the city but it also presents the very real risk of collapsing both the dark cave and the cave housing the sacred Hindu shrines. Public outcry from conservationists and worshipers has led to a temporary injunction being placed on the project.
The future of the Batu Caves as well as Malaysia’s limestone cavern ecosystems as a whole is rather uncertain. If you are a traveler to Malaysia, we highly recommend doing yourself and the caves a favor by taking the well-guided and fascinating dark cave tour (35 ringgits) when visiting the Batu Caves, a must see if you are in Kuala Lumpur. With advanced notice adventure tours are available that take you further into the dark cave system.