General characteristics of phylum Arthropoda:

(i) They are triploblastic, bilaterally symmetrical and metamerically segmented animals with haemocoel body cavity.

(ii) The body segments are grouped into cephalothorax and abdomen or into head, thorax and abdomen.

(iii) They have a complex muscular system with exoskeleton for attachment, striated muscles for rapid actions and smooth muscles for visceral organs.

(iv) Sexes are usually separate and sexual dimorphism is marked in several forms.

Examples: Prawn (Palaemon) and centipede (Scolopendra).