Spider

Spiders are arachnids, not insects, and belong to the order Araneae. More than 52,000 species have been described, living on every continent except Antarctica. Unlike insects, spiders have eight legs and a body divided into two main parts instead of three. Most species possess eight simple eyes, although the number and arrangement vary.

They produce silk from specialized organs called spinnerets located at the end of the abdomen. Spider silk is remarkably strong and flexible, and different kinds of silk are used to build webs, wrap prey, protect eggs or create safety lines while climbing. Spiders occupy a wide range of habitats, from forests and deserts to grasslands, caves and even human buildings.

Most spiders are predators that feed mainly on insects and other small invertebrates, helping keep many animal populations under control. Although web-building spiders are well known, many species actively hunt without using a web to capture prey. Nearly all spiders produce venom to subdue their food, but only a small number have bites that can be medically significant to humans.

Rather than chewing, they inject digestive fluids into their prey and then consume the liquefied tissues. Females usually place their eggs inside silk egg sacs that protect the developing young until they hatch. Thanks to their diversity and ecological role, spiders are among the most important natural predators in terrestrial ecosystems.