viernes, 18 de marzo de 2011

Spiders facts

Spiders aren't the most appealing creatures, but they do serve their purpose ecologically. As frightening as they might be to most people, spiders are fascinating creatures to learn about.

• Spiders have existed for at least 350,000 years. There are approximately 37,000 species of spiders in the world.


• Spiders play an important role in the environment by consuming insects. As a group, spiders eat more insects than birds.


• Spiders are not actually considered to be insects. They are arthropods. Spiders have two main body parts consisting of a combined head, thorax--called the cephalothorax--and the abdomen. The spider has no internal skeleton. The body is covered with a hard outer covering called the exoskeleton.


• Spiders have four pairs of legs. Most spiders have 8 eyes but some have less. The Brown Recluse spider has 6 eyes.


• All spiders are carnivorous predators. Most are nocturnal hunters. Spiders can survive for several weeks without food. The Brown Recluse spider has a violin shape on the upper side of the cephalothorax. The Black Widow has two reddish markings that join to form an hourglass shape.see more at what do spiders eat.