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
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)