THE ZEBRA-SPIDER in 3D
|One of the commonest spiders you can find around the house is the zebra spider, Salticus scenicus. You can find it sitting on the wall or on a window-frame but it is not so easy to spot. It is a tiny spider with a body size that doesn't exceed 8 millimetres, but you can use a hand lens to its spectacular appearance. The zebra spider belongs to the jumping spiders. It does not make a web but stalks its prey. It will use a silk thread as an anchor. When it spots an insect it will slowly try to approach it. Now and then when it is out of the victim's sight the zebra spider will run. When it is within reach it will jump and paralyse the prey with its venomous 'jaws'.|
|To be able to capture prey like this jumping spiders rely on superb eye sight. Their eyes are truly remarkable. The front pair is the most impressive. They can be regarded as the best eyes you can find in any arthropod. They work as a telephoto lens. The retina inside the eye can move in 3 dimensions enabling the spider to look in all directions and focus on a subject. When you approach a jumping spider it will position itself so it can observe you. The 6 other eyes are positioned around the head for a 360 degrees vision.|
A male zebra spider (left) is hiding its huge chelicerae ('jaws') behind its pedipalps (the little boxing gloves'). The males use the large chelicera for battles. The pedipalps (often called just 'palps') are secondary sexual organs. The spider deposits its sperm on a small web and then uses a special reservoir within the pedipalp to carry its seed around. It will then try to mate with a female zebra spider. Mating is often a dangerous procedure. The male spider uses its front legs to make all kinds of signals to avoid being mistaken for a prey. It has to try to reach the reproductive organ of the female, called the 'epygine', which is situated under the abdomen. When the sperm is transferred the female will carry it in a special compartment and will use it when she is ready to fertilise her eggs.
Since jumping spiders rely so much on their sight they can easily be fooled by using a mirror. The male will try to attack its own reflection.
The images were taken from living spiders. These pictures will be part of a CD ROM with 3D images of insects spiders and other small creatures. This CD ROM will be available later this year!
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