Return of the tarantula
It is not the attractive “charismatic” creatures such as the sleek leopard or the majestic elephant that lured them, but the small, neglected and unsung creature many would crush under their feet. Their arduous search into numerous nights, going into weeks, months and a year, however, has not only brought the tarantula under the torchlight but also the research team into the limelight.
While looking for tarantulas in the wild by scrutinising tree-holes, tree trunks and tree barks where they usually live, the research team headed by Ranil Nanayakkara of Biodiversity Education and Research (BEAR) saw to their delight not just a mother-tarantula but about 15 spiderlings of a particular species thought by some to be extinct or on the brink of extinction.
Soon after, the team also found about 15 more male, female and juvenile tarantulas within a 10km radius around the female with the spiderlings, the Sunday Times understands, with the “discovery” being special because this species was also believed to be restricted to Haragama in the Kandy district, with their numbers dwindling.
“It is the tarantula species Poecilotheria smithi and we found them in the Matale district an aerial distance of 30 km from Haragama,” says Ranil, declining to give the specific area because they are still writing up the paper and conducting the taxonomy work and are fearful that there may be attempts to collect them illegally for the pet trade.
The team’s research includes the determination whether the P. smithi tarantulas found recently are a “relict population”, according to him.
Ranil then leads us back in time to the information collated about tarantulas in Sri Lanka. It had been way back in 1803 that tarantulas of the genus Poecilotheria were recorded here. Till 1885, this genus was monotypic, consisting of the single species P. fasciata and considered distribution-specific to Sri Lanka. In early 1895, R.I. Pocock had described the species P. subfusca and in 1899, the species P. ornata. In 1913, Strand had found P. uniformis and by 1996, more than 100 years after the very first discovery, British scientist Peter Kirk had described P. smithi with a type specimen collected from Haragama in the Kandy district. It was Kirk again in 2001 who found P. pederseni.
Even though there were several studies from 2002 to 2005, P. smithi had not been spotted in the wild elsewhere, with only a single specimen – a freshly moulted female – being discovered at Haragama, with researchers assuming that it was endangered and attributing its restriction to Haragama, to deforestation.
It was then that alarm signals had begun to appear, with the International Union for Conservation of Nature (IUCN) placing P. smithi on the “critically endangered list”, the Sunday Times learns.
August 2011 saw Lead Researcher Ranil along with co-founder of BEAR, Nilantha Vishvanath, and field assistant T.G. Tharaka Kusuminda under the guidance and supervision of Dr. G.A.S.M. Ganehiarachchi of the University of Kelaniya looking for the Poecilotheria genus in an island-wide search, for during the war lasting nearly 30 years no one had checked out the whole country.
The researchers are being supported by both the Department of Wildlife Conservation and the Biodiversity Secretariat and have been helped much by the Head of the Biodiversity Unit of the Customs, Samantha Gunasekara.
With their voices tinged with excitement, both Ranil and Nilantha explain how they came across P. smithi in the Matale district last month. Their deduction is that this is a “relict population” separated from the original group in the Kandy district by deforestation and urbanisation. The local perception had been that due to these areas being cleared up for fruit orchards and other cultivations, this species was on the verge of extinction. A relict population is a species of an earlier time surviving in an environment that has undergone considerable changes.
Explaining the finer details about these tarantulas which are nocturnal and arboreal, inhabiting tree holes, bark peel-offs and on occasion houses, Ranil says the females are significantly larger than the males and more colourful as well. They don’t weave webs to trap their prey but depend on speed to ambush it and envenom it. “These tarantulas are known for their colourful markings, lightning speed and potent venom.”
The female has its own micro-habitat which is a small area that is different to its surrounding areas with regard to environmental conditions, according to him. Citing the mother-tarantula found by them as an example, this scientist points out that she would remain in her habitat while the males who are nomadic would loiter in the same area, attracted to the female. Ranil who has moved from land to water as a researcher and is now back to land, seems to be one of a kind since he has carried out groundbreaking research on maritime as well as terrestrial mammals and other animals.
He has researched extensively on dugongs and cetaceans out at sea.Moving back to his current research, Ranil points out how tarantula species could be transported accidentally from their habitats to Colombo or other urban areas with loads of bananas or timber.
The island-wide survey was launched after their interest in tarantulas was kindled when Ranil was offered a dead tarantula literally on a platter when he was in the north. At that time it led to the discovery of what they think are two new species, P. cf regalis and P cf Hanumavilasumica in the north.
The survey due to end in November will hopefully be extended by another year due to the current findings, Ranil says, adding that what is unique is that all earlier studies as well as discoveries had been by foreigners but this is being carried out by a local team.
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