Arthropods contain jointed appendages. The exoskeleton is made of chitin. As the animal grows it must molt.
Arthropods contain well developed sense organs.
Compound eyes, sensory antennae, and tympanic membranes. An open circulatory system is found in all arthropods. The blood is propelled through the body by a tubular heart and collected in areas called sinuses. They contain a variety of respiratory organs such as book lungs, trachea, spiricles and gills. They contain bilateral symmetry.