A lot of people think that Spiders are insects. But they are not. Spiders are predatory invertebrate arachnid arthropods in the order Araneae. The body of a spider contains two parts - the head part and the abdomen part. The two parts are connected through a stalk.

On the head part there are four pairs of simple eyes. Below on the head part there are two pairs of appendages. On each of the first pair of appendages there is a fang. This one is connected to a poison gland. The next pair of appendages is the leg like mouth organs that are also used as feelers and sex organs for the male spiders. The head part also has four pairs of legs.

The abdomen part also has appendages that are used in secreting silk. There are forms of lungs in this part of the spider. The female genitals are also located in the middle of the abdomen part. The rest of the abdomen part is mostly part of the digestive system.

Spiders can only digest liquid food. The venom only incapacitates the prey and has no part in the digestions. Most spiders rip their pray into pieces with their teeth. They then regurgitate enzymes that brake down the tissue of the prey.

The liquid tissue is then sucked back into the spider together with the enzymes. The spider then recirculate this liquid back on the pray so that more tissue are exposed to the enzyme and more of the will be liquefied.

The digestive system of a spider goes from the mouth to the anus. Around the stomach there are strong muscles that can contract and thus get a strong sucking action that bring in the liquefied food into stomach.

The spiders have a filter in their mouth to make sure that only particles that are smaller than one micrometer can get past the mouth and into the stomach. The filter is made up of a large number of the hair surrounding the mouth and of palate plates inside the mouth.

Spiders have a very large part of their stomach where they can store the liquid food. When the spider is well feed most of the abdominal part consists of food. This makes the spider able to survive during a very long time without food.

The bodies of most spiders are less then a centimeter but the large ones can have a body up to 9 centimeters. All spider use silk. Most spiders use it in webs to trap prey but it is also used to climb and to hold the sperms. Spiders only eat living prey.

Most spiders have venom to kill their prey or to protect themselves. The bite from larger spiders can often be painful but they are usually not dangerous to humans.

The teeth from most spiders are too small to get through the human skin. There are only about 200 species that have venom that could be dangerous or cause health problems to humans. The most common species that are dangerous to humans are the black widow spider, the brown recluse spider and the funnel web spider.