Arachnid Arachnid Arachnids () are a class (Arachnida) of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Almost all adult arachnids have eight legs, although the front pair of legs in some species has converted to a sensory function, while in other species, different appendages can grow large enough to take on the appearance of extra pairs of legs. The term is derived from the Greek word ("aráchnē"), from the myth of the hubristic human weaver Arachne who was turned into a spider. Spiders are the largest order in the class, which also includes scorpions, ticks, mites, harvestmen, and solifuges. Almost
Terrestrial locomotion The most diverse group of animals on earth, the insects, are included in a larger taxon known as hexapods, most of which are hexapedal, walking and standing on six legs. Exceptions among the insects include praying mantises and water scorpions, which are quadrupeds with their front two legs modified for grasping, some butterflies such as the Lycaenidae (blues and hairstreaks) which use only four legs, and some kinds of insect larvae that may have no legs (e.g., maggots), or additional prolegs (e.g., caterpillars). Spiders and many of their relatives move on eight legs – they are octopedal. However, some creatures