Spiders

Spiders

Introduction Do you jump when a spider crosses your path? Spiders may make some people nervous, yet they are mostly harmless to humans. More than forty thousand kinds of spiders live all over the world. They range in size from the head of a pin to a large dinner plate. The smallest may be lighter than a feather, while the heaviest can weigh as much as a softball.

Traits Although spiders look like insects, they are different in many ways. Spiders have eight legs. Insects have only six. Spiders have two body parts including the head. Insects have three body parts including the head. Most spiders have eight eyes, and most insects have only two. Spiders do not have wings. Most insects do.

Life Cycle A female spider can lay thousands of eggs. After they hatch, the babies often stay near the mother until they can live on their own. Many spiders only live for a couple of years. Some, such as female tarantulas, can live up to thirty years.

Diet Spiders eat about half a billion tons of insects each year. Without spiders, insects would destroy much of our food crops. Spiders also keep the number of pests such as mosquitos under control. Most spiders use their fangs to bite prey and inject venom-a poisonous liquid. Fangs work like a needle.

Webs and Silk Some spiders make webs, which come in many beautiful shapes. These spiders use special body parts to make silk for their webs. The webs trap insects for them to eat. Many spiders add a sticky glue to the web. This makes it hard for insects to escape. Once an insect is caught, the spider wraps it tightly in silk.