Arachnid and that there may be up to 600,000 in total. 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,
Bird feet and legs the foot may be close to 0 °C (32 °F). However, for cooling, this heat-exchange network can be bypassed and blood-flow through the foot significantly increased (giant petrels). Some birds, also excrete onto their feet, increasing heat loss via evaporation (storks, New World vultures). Bird feet and legs The anatomy of bird legs and feet is diverse, encompassing many accommodations to perform a wide variety of functions. Most birds are classified as digitigrade animals, meaning they walk on their toes, rather than the entire foot. Some of the lower bones of the foot (the distals and most of the metatarsal)