Wednesday, 5 September 2012

How do spiders build their webs?


Garden Spider in web

So how do spiders do it?
I have been studying nature all my life and am still totally amazed by spiders. I am astounded by what they do. Their webs are a miracle I am sure you will agree?
There is a Garden Spider female with a web hanging over my balcony and I have wondered how she created it. The balcony is around 14 ft wide, and I know that having measured it, but somehow the spider has lines to both walls and another to the ceiling, as well as one to the balcony railings.
She is suspended in space with at least 6 ft between the one wall and the centre of her web. There is something like a 40 ft drop below into a car-park.

To weave a web

Apparently the spider puts out a line of silk that may be carried by the breeze to a nearby wall, trunk, twig, leaf or other solid surface. As soon as it hits the spider senses this and runs down it as well as creating another thread to make the connection stronger.
I have never seen this myself whilst observing spiders in the wild but have seen it captured on film in a presentation by David Attenborough so I know this is how it is done. It has been filmed in time-lapse and speeded up so we can view the process.
The spider creates other main lines below and to the side of the web and then starts filling in the rest of it around the central hub point. The spider uses as many as six different types of thread to create its work and there can be as much as 60 metres of thread in a single web. This is how the orb-weavers go about it and they make fantastic webs with intricate webbing and precision.
An orb-weaver can complete making a web within an hour after it has created the basic lines to hold it in place. Some orb-weavers make a new web every night.
Orb-web spiders make their webs under the cover of darkness for obvious reasons. They are a lot less likely to be seen moving about then, whereas in the daytime a hungry bird might spot them.
I love to see spider webs when they are covered in dew-drops. They look really magical glistening in the sunlight of an early morning, as if they weren't already magical enough!
In the UK there are lots of Garden Spiders about in late summer and early autumn. The females can be recognised by their larger size. They have a white cross on the back of their bodies too.
There are other types of webs including tunnel webs that do not appear so complex but the system of spinning a web is pretty miraculous I think even if some sorts of webs do not look as attractive to the human eye. And then there are spider types such as the Hunting Spiders, Crab Spiders and Wolf Spiders that do not build webs but rely on their hunting skills to catch their prey.

Tent-web spiders

In Tenerife where I am living we have a very common spider which is one of the tent-web spiders. Cyrtophora citricola tends to live in communities of males and females. They spin large sheet-like webs that they drape over foliage and hence the name "tent-web."

Tent-web Spider

The females spin cocoons in which they lay their eggs and these hang in the middle of their webs where they can stand guard over them.
This particular species, which is also found in the other Canary Islands and in Africa, tends to spin its webs in clumps of Prickly Pear cactus (Opuntia ficus-barbarica) and in the massive spiky leaves of the Century Plant (Agave americana). Living like this presumably offers the spiders some protection from predators and humans too! Many people are scared of spiders and kill them but I think they are amazing little animals!
Copyright © 2012 Steve Andrews. All Rights Reserved.
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