Chelicerata is the group of arthropods that includes the marine sea-spiders and horseshoe crabs and the terrestrial arachnids (spiders, mites, scorpions and their relatives). They have two main body regions, and the arachnids typically have eight walking legs. They are covered by a jointed exoskeleton and grow by periodic moulting. Chelicerates are typically predaceous and most terrestrial forms ingest only liquefied food. Next to insects, they are the most diverse and numerous animals.