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
Threatened arthropods Thus extinction of arthropods species threaten to make extinct hundreds of thousands, if not millions, of higher order birds, amphibians, reptiles and mammals. There are several pathways of endangerment for arthropods; however, most of them stem from the pressures of an expanding human population and resulting actions humans take to produce food, housing, transportation and recreation. Probably the greatest hazard to arthropod survival is agriculture, due to the ever increasing demand of the human population to feed its expanding numbers. Agriculture typically results in a monoculture that cannot support the biodiversity nurtured by the predecessor natural environment. Normally arthropods represent