Exploring the World of Spiders

spider, (order Araneida or Araneae), any of more than 46,700 species of arachnids that differ from insects in having eight legs rather than six and in having the body divided into two parts rather than three. The use of silk is highly developed among spiders. Spider behavior and appearance are diverse, and the araneids outside Europe, Japan, and North America have not been thoroughly collected and studied.