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Wednesday, December 8, 2010

Spiders galore

 Photo's by Lim Jin Bing

Deception: A spider demonstrates beetle mimicry

By Sunita
 The first thing I had learnt about spiders was that they are not insects because they have 8 legs and only two body parts. They are a diverse lot and can be found almost everywhere in the world. They prey and are preyed upon. And just like any other organisms they need to defend themselves against their enemies or potential predators.
During Mr Joseph Koh’s talk on October 26, 2010 it was interesting to discover that the way a spider protects itself is akin to something a person would see or go through when in the army. As I love pilfering my brother’s books on the SAS (Special Air Service), my immediate thoughts were that they (the SAS) must have at one point or another emulated the spider’s techniques!
Spiders build shelters or hide themselves to visually conceal them from birds or wasps, very much like hiding in the trenches or bushes. Hiding in burrows also has advantages especially if the burrow is deep and the enemy is unable to reach through it. Silk funnels, very much like the ‘bubu’ that is used to catch fish, are also good places to retreat into when under threat.
Concealment:A spiderhides in a leaf retreat

A warning system likened to a trip-wire or radar will give a spider ample time to run away or hide. The extensive network of fine silk webbing has several fine long silk web lines attached to it. These lines extend a distance away from the main web and when an insect – regardless if food or foe – comes near the vicinity of the main web and trips over the line, whoop! – off the spider goes into hiding.
Having camouflage also helps the spider from being spotted. Camouflage ‘fatigues’ seen in the huntsman spider comes in all colours and textures. Some resemble sticks, leaves and branch nodes. Others resemble insects by waving the first pair of legs like an ant antennae, a deceptive move to help them live amongst ants. They also secrete formic acid like ants. To remain undetected, spiders may even mimic plant parts such as flowers. This certainly aids in ambushing the unsuspecting insect predator or a potential victim in a flash. Mimicry is not just limited to plants. It has been reported that some spiders look like bird droppings, even adopting the smell of one and soil lumps on the forest floor!
One species of spider commonly called the lichen spider is known to flatten itself against the surface it is on as such that it does not cast a shadow. ‘Armaments’ acquired from modified structures on a spider provide protection by making them indigestible. Other deterrence includes adopting threat postures to scare off any potential threats. Being large (although slow) also helps in deterring itself from being devoured.
So, spotting spiders may not be easy in the beginning but with patience and plenty of practice you’ll bound to find one – hiding or lurking somewhere…. waiting for you.
Big web:A spider stays hidden within a leaf in the middle of an intricate web.

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