In this article we will discuss about the external structures of Crustaceans, Myriapods, Insects and Chelicerates. 1. Head: In Crustacea, the head is formed by the fusion of six segments. The organisation of head varies in different Crustaceans. In Cephalocarida and Branchiopoda, the head is free from thorax. In free-living Copepods, only the first thoracic […]