Arachnids are any of the joint legged invertebrate animals. All have 8 legs although some use their front legs as a sensory function.
Arachnids are a class (Arachnida) of joint-legged invertebrate animals in the subphylum Chelicerata. All 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.
Contributions by Sarefo, IronChris, and Vae victis.