Spiders are classified as arachnids, a class of arthropods that also includes scorpions, mites, and ticks. They belong to the order Araneae, which is the largest order of arachnids and ranks seventh in total species diversity among all orders of organisms. Spiders have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are found worldwide on every continent except for Antarctica and have become established in nearly every land habitat. As of August 2022, 50,356 spider species in 132 families have been recorded by taxonomists. Taxonomically, spiders belong to the kingdom Animalia, phylum Arthropoda, class Arachnida, and order Araneae.