Blastopore forms anus
Nerve not around gut
Exoskeleton
Schizocoely
Coelom (of some sort)
Spiral cleavage
Cephalization
Molecular characters
Radial cleavage
Ecdysis
Bilateral symmetry
Nerve surrounds gut
Triploblastic
Lophophore (lost in many)
Dorsal nerve
Trochophore larva (lost in many)
Determinate fate
Indeterminate fate
Ventral nerve
Blastopore forms mouth
Enterocoely