Arthropods contain jointed appendages that are modified in different species to carry out certain functions. The exoskeleton is made of a mucopolysaccharide called chitin .
Arthropods contain well developed sense organs.
Compound eyes, sensory antennae, and tympanic membranes keep most arthropods in communication with their environment. An open circulatory system is found in all arthropods. These are very few blood vessels in the arthropods. They contain a variety of respiratory organs such as book lungs, trachea, spiracles and gills. They contain bilateral symmetry.