Superphylum Ecdysozoa

The superphylum Ecdysozoa includes the nematode worms and the arthropods, both of which have a tough external covering called a cuticle.

Nematodes are parasitic and free-living worms that are able to shed their external cuticle in order to grow.

Arthropods are the largest grouping of animals all of which have jointed legs and an exoskeleton made of chitin.

The Phylum Arthropoda includes a wide range of species divided into the subphyla: Hexapoda, Crustacea, Myriapoda, and Chelicerata.