(i) These animals are bilaterally symmetrical and segmented.
(ii) Body is covered with chitinous exoskeleton.
(iii) One or two pairs of jointed legs are present.
(iv) The body cavity is blood-filled and is called haemocoel.
(v) Body bears jointed appendages, and is divided into head, thorax and abdomen.
(vi) Circulatory system is open, i,e. blood doesn’t flow in blood vessels.
Examples: Palaemon, cockroach and butterfly.