Spiders are not insects, but air-breathing arthropods with two body segments and eight legs. So far, about 40,000 species have been discovered, with the smallest one, dwarf spider, being less than 1 mm (about .05’’) in body length, and the largest one, tarantula, with body lengths up to 90 mm (about 3.5’’). In captivity tarantulas can live up to 25 years, but lifespan of most species does not exceed 2 years.

Spiders are predators preying mostly on insects and other spiders, but some large species eat birds and lizards. Spiders have a very narrow gut that can’t cope with solid matter, and because of that they liquidize their food with enzymes.

Spider webs are made of silk mainly composed of a protein. Spiders extrude it form their spinneret glands at their abdomen with each gland producing a thread for a special purpose. There are several types of spider webs, including spiral orb webs, cobwebs, tubular webs, domes and funnels. Normally, spiders do not stick to their own webs, but they are not immune to their own glue either.

Male spiders inject sperm into females’ genitalia through the appendages below their mouth. Females may lay up to 3,000 eggs in egg sacs made of spider silk. Most species care for their eggs by attaching them to their webs or hiding them in the nests. In some species females eat their partners after mating.