Giant web probes spider's sense of vibration

By Jonathan Webb

Science reporter, BBC News, Baltimore

19 March 2016 

Inside a lab in Oregon, US, a two-metre spider web made of aluminium and rope is beginning to unlock how orb weavers pinpoint struggling prey.

When an unlucky insect lands in a web, it is vibrations that bring the spider scuttling from the centre of its trap.

How spiders interpret those signals is a mystery - so physicists have built this replica to figure it out.

They unveiled the design and their first results on Friday at a meeting of the American Physical Society (APS).

"We wove the web using two different kinds of rope, the same way as spiders use two different formulations of silk," said Ross Hatton from Oregon State University.

The radial strands that fan out from the centre are made of stiff, nylon parachute cable, while elastic bungee cords make up the "spiral strands".

The whole thing sits in an octagonal aluminium frame, with a speaker strapped to one corner to deliver some hefty vibrations.

"It's a big subwoofer, so we can give a fairly good push to the web - there's quite a bit of force in it," Dr Hatton told BBC News, at the APS March Meeting in Baltimore.

At the centre of the web sits an artificial spider - a simple eight-legged frame, which doesn't move but detects vibrations in the threads, just like a real spider.

Continued ...

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.

Continued:  http://www.wildlifeextra.com/go/news/orb-weaver-london.html