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
Bird feet and legs the rear like the propeller on a motorboat. Grebes and many other waterfowl have shorter femur and a more or less narrow pelvis, too, which gives the impression that their legs are attached to the rear as in loons. Because avian forelimbs are wings, many forelimb functions are performed by the bill and hindlimbs. It has been proposed that the hindlimbs are important in flight as accelerators when taking-off. Some leg and foot functions, including conventional ones and those specific to birds, are: Typical toe arrangements in birds are: The most common arrangement is the anisodactyl foot, and second among