A natural order of the class Arachnida, also called Araneida, commonly known as the spiders. These animals are widespread over most of the land areas of the world and are well adapted to many different habitats. They are known to be one of the oldest of all groups of arthropods, and their remains are known from the Devonian and Carboniferous geological deposits. Through successive geological periods spiders have become adapted to insects as their chief source of food. On the other hand, certain insects consume the eggs of spiders, others parasitize the eggs, and still others capture adults and place them in their nests for food for their young.