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,
Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness of the animals gather. Octopuses are, he notes, inquisitive, observant, even friendly, but the architecture of their nervous systems is entirely different from the vertebrate plan. The octopus's intelligence is distributed throughout its body: there are almost twice as many nerve cells in their eight muscular arms as in their brain. Intelligence is, Godfrey-Smith argues, predicated upon the "complex active bodies". Three groups of bilaterian animals with that kind of body plan evolved in the Cambrian period, some 500 million years ago: the arthropods (such as crabs and insects), the vertebrates, and within the molluscs, the cephalopods. Godfrey-Smith disagrees with