Spider Spider Spiders (order Araneae) are air-breathing arthropods that have eight legs and chelicerae with fangs able to inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other orders of organisms. Spiders are found worldwide on every continent except for Antarctica, and have become established in nearly every habitat with the exceptions of air and sea colonization. , at least 45,700 spider species, and 113 families have been recorded by taxonomists. However, there has been dissension within the scientific community as to how all these families should be classified, as evidenced by
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