Spiders have a great importance in the ecological chain because they have a great ability to watch other insects and to feed themselves on them.

Spiders live in dark and hidden places. They eat crickets, flies, bees, and butterflies. Spiders are necessary for the ecological balance of our planet Earth.

We know that the spider fabrics its tile to catch in it the insects. It is very interesting to see the ability that it has to do it. The spider makes the tile with silk that it produces inside its body. This tile is more resistant than steel and it is also flexible.

Spiders exist in a variety of colours, from opaque gray, coffee and black, to a brilliant red, green and yellow . Its body is divided in two regions: the cefalotórax, with the head and the thorax, and the abdomen which is similar to a small globe and generally, covered by thick hair. It has eight simple eyes, four pairs of legs and a pair of clamps near the mouth.

The spider is an animal that has positive and negative aspects .

Positive: spiders eat many insects, which aids to control the amounts of these. The use of spiderpoison in some medical researches has produced several chemical products that can be useful to control or to treat diseases of humans.

Negative: the puncture of a spider can cause pain, but in most of the cases the poison it transmits does not make any damage. Only some spider give off poison that can cause very harmful reactions in humans .

Within the family of the arachnids we have the scorpion. It is bigger than the spider. The biggest can measure 20 centimeters and the smallest about six.

They live in countries with a warm climate; during the day they take refuge under stones and at night they leave to hunt insects and spiders that will become their food. If a scorpion attacks, its poison is very dangerous.