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
Threatened arthropods Thus extinction of arthropods species threaten to make extinct hundreds of thousands, if not millions, of higher order birds, amphibians, reptiles and mammals. There are several pathways of endangerment for arthropods; however, most of them stem from the pressures of an expanding human population and resulting actions humans take to produce food, housing, transportation and recreation. Probably the greatest hazard to arthropod survival is agriculture, due to the ever increasing demand of the human population to feed its expanding numbers. Agriculture typically results in a monoculture that cannot support the biodiversity nurtured by the predecessor natural environment. Normally arthropods represent