Question

The three major clades of bilaterian animals are the __________.

Answer 1

The three major clades of bilaterian animals are the ecdysozoa, lophotrochozoa, and deiterstomia. 
Ecdysozoa are organisms that include insects, crustaceans, chelicerata, and myriapods. Lophoytochozoa include fossil organisms. Deiterstomia include chordata, echinodermata, and hemichordata.
Bilaterian animals have bilateral symmetry, meaning that they have a head, and a tail, as well as back and belly.