December 14, 2006

Spiders characteristics

Spiders sizes

The biggest spiders can reach a size of 75 mm of length with a space of 255 mm between their legs. Female spiders tend to be bigger than their males mates.

Spider groups

Spiders are divided into three main groups:

- Primitive or rare spiders: They usually come from tropical Asia.
- Migalomorphes
- Araneomorphes

Spider jaws

The primitive spiders and the migalomorphes have jaws that can beat down their preys and drag them over the floor or any surface.

The jaws of araneomorphes spiders work independently over the surface. Each moves towards the other when they are catching and trespassing the prey.

Spider eyes

Spiders have a pair of main eyes that are in the central part of the first raw, that have a crystalline and a retina. These eyes are very developed in furtive hunter spiders. The rest of eyes are secondary, with retina cells sensitive to light that make them get away from light.

Spider senses of smell and touch

It is matter of controversy whether if smell ands taste are separated in spiders. What we do know is that spiders taste through the esophagus and any food with bad taste is quickly expelled. But they have also a sense of taste and smell on little orifices of their legs.

Spider sensorial receptors

Spiders so not hear like us; they feel vibrations transmitted by air or by the surface they are on. This sensorial skill is located in a number of different receptors extended throughout their bodies, but especially in the appendixes, where there are some structures that are in some segments of the leg that consists of a vertical hair in a hole. This allows the spider to feel the vibrations of the place where it is walking. It only takes tot ouch one to get a quick response. They are cold-blooded, so they have to keep their bodies warm until certain limits.


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