A test to see whether the embryo exhibits spiral cleavage or radial cleavage.
Eight-cell stage in the development of animals differ between protostomes and deuterostomes. Cleavage of Protostomes is spiral and determinate, while in Deuterostomes is radial and indeterminate.
The stage of coelom formation also differs: in Protostomes it is schizocoelous-mesoderm forms coelom; in Deuterostomes it is enterocoelous-archenteron form coelom.
Final and main dfference:
• Protostomes-mouth develops from the blastopore
• Deuterostomes-anus end develops from blastopore.