Making up around 75% of all animal species in the world, arthropods are are a vast phylum of the kingdom Animalia. The name comes from the Greek words “arthro”, meaning joint, and “podos”, meaning legs. While they all share segmented bodies with joined legs, members in this phylum vary wildly, from butterflies and millipedes, to scorpions and lobsters. They are also all invertebrates, which means that they do not have backbones. Instead, they use hard exoskeletons to protect themselves, which are made out of chitin. Because these exoskeletons are relatively inflexible, arthropods molt as they grow larger, which means they shed their exoskeletons.