Saturday 19 January 2013

Rare and spectacular spider find in 150 year-old tombs in London!


First record of orb weaver spider in London
January 2013. A large, rare spider has been recorded for the first time in London - deep in tombs at Highgate Cemetery.

As part of the Wild London Inclusive London project, staff at London Wildlife Trust have been working with the staff and local community of Highgate Cemetery since last summer. During a bat survey in December, Trust staff came across a population of large spiders in the vaults of the Egyptian Avenue at the Cemetery.

Britain's largest orb weavers
Interestingly, these orb weavers are the species Meta bourneti, the rarer of two species of Meta (Britain's largest orb weavers). The identity of the spider was confirmed by Edward Milner, Spider Recorder at the London Natural History Society - and it is the very first record of the species in London!

Meta bourneti is particularly fascinating because, due to its origins as a cave-dweller (also known as a cave spider), it requires total darkness. Even an outdoor night time environment is too bright for it, so the spiders never leave the tombs.

A sealed vault provides a perfect breeding ground. Most of these vaults - walk-in tombs designed to house around four coffins - have not been opened for several years. And, because the structures date from the late 1830s, it's quite possible the spiders discovered have lived in the tombs for at least 150 years without being detected. Meta spiders are amongst the largest spiders found in Britain. They prey on small insects and woodlice. The females produce teardrop-shaped eggsacs, which hang suspended on a silk thread from the roof of their dwelling. When the spiderlings first emerge they are attracted to light, unlike the adults which are strongly repelled by light. This helps the spiderlings find new areas to colonise. Meta bourneti also need constant temperatures and high levels of humidity. Elsewhere in the UK, these spiders can be found in sewers, old cellars and abandoned railway tunnels.

Undisturbed for 150 years
A sealed vault, on the other hand, provides a perfect breeding ground. Most of these vaults - walk-in tombs designed to house around four coffins - have not been opened for several years. And, because the structures date from the late 1830s, it's quite possible the spiders discovered have lived in the tombs for at least 150 years without being detected!

30mm in diameter
The find is made even more exciting by the spider's large size. Most new spider records are for tiny species, but Meta bourneti measures over 30mm in diameter with leg-span included.


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