What are Three specialized parts of an arthropods?

Fact is, arthropods make up the largest animal group on earth.

Crabs, scorpions, crayfish, dragonflies, arachnids, krill, shrimp are just a very few arthropods. Any animal with a segmented body and six or more legs is an arthropod.
Arthropods are called the eumetazoa, which means that they develop germ layers and have vascular tissues and organs develop. Arthropods are triploblastic (form three germ layers, endoderm, mesoderm, and ectoderm). They have an exoskeleton which molts, contain compounds eyes, and jointed appendages. Phylum Arthropod contains classes such as Insecta, Arachnida, and Crustacea. Insecta would include bettles, butterflies, and grasshoppers. Arachnida would include Spiders, Scorpions, and Mites. Crustacea would include, Lobsters, Crabs, and Shrimp.