-They are triploblastic in nature
-They are coelomates, although the coelom is enormously reduced.
-Metameric segmentation is present
-Bilaterally semetrical
-Presence of three body divisions: head, thorax and abdomen
-Possession of exoskeleton of chitin and sometimes calcareous matter
-May be rigid, stiff or flexible
-Each segments typically bears a pairs of jointed appendages
-Jointed walking legs are used for locomotion, feeding or sensory purposes.
-Their main body cavity is haemocoel
-Sexual reproduction and internal fertilization are present
-Parthenogenesis is present in some members
-They are widely distributed
-Wings may be present in some members
-Largest group of animals