Threatened arthropods and described. The total number of living arthropod species is probably in the tens of millions. One conservative estimate puts the number of arthropod species in tropical forests alone at six to nine million species. As a consequence of all of the above, most published estimates of the total number of endangered insects and arachnids are probably low by at least an order of magnitude. Conservatively at least eighty percent of all living animal species are arthropods. Since arthropods constitute the majority of the faunal biomass on Earth, their role is vital to the survival of large numbers of insectivores
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