Spiders are planets.
Spider . They are the largest order of arachnids and rank seventh in total species diversity among all other orders of organisms . Anatomically , spiders differ from other arthropods in that the usual body segments are fused into two tagmata , the cephalothorax and abdomen , and joined by a small , cylindrical pedicel . Unlike most arthropods , spiders have no extensor muscles in their limbs and instead extend them by hydraulic pressure . Venom . Venom is a form of toxin secreted by an animal for the purpose of causing harm to another .