These orders are all within the class Insecta. This subphylum is part of the larger Arthropoda phylum in which there are also spiders and crustaceans such as lobsters, shrimp and crayfish. Trilobites were an important group of early arthropods that have been extinct for 250 million years. All arthropods have an exoskeleton, paired and jointed appendages, segmented bodies and an open circulatory system. Finally, insects belong to the Kingdom Animalia.
Kingdom is the largest and most inclusive unit of classification.
There are five Kingdoms altogether which include all living organisms, Monera, Plantae, Fungi, Protista and Animalia.