Organisms in the phylum Arthropoda, arthropods, are invertebrate animals having an exoskeleton, a segmented body, and jointed appendages. The phylum Arthropoda includes the insects, arachnids, myriapods, and crustaceans. Arthropods are characterized by their jointed limbs and cuticle made of chitin (which is grown by molting) often mineralized with calcium carbonate. They are also the most successful animals on the planet. They're also important members of meiofauna as they channel nutrients to larger consumers in the food web.