Let me share with you a difference between spiral cleavage and radial cleavage.
| Aspect | Spiral Cleavage | Radial Cleavage |
| Type of cleavage | Asymmetrical | Symmetrical |
| Orientation of cleavage | Diagonal or oblique to the animal-vegetal axis | Perpendicular or parallel to the animal-vegetal axis |
| Cleavage pattern | Cells divide at an angle to the previous division plane | Cells divide either directly above or below the previous division plane |
| Development of blastomeres | Cells of one hemisphere are shifted with respect to the other hemisphere | Cells are relatively symmetrical in relation to each other |
| Fate of blastomeres | · Indeterminate
· Different developmental fates for different cells |
· Determinate · Initially similar developmental fates for all cells |
| Embryonic morphology | Often leads to a spiral arrangement of cells | Radial symmetry in the early embryo |
| Regulative development | Less regulative development; removal of blastomeres may affect the final structure | More regulative development; removal of blastomeres may not severely affect the final structure |
| Examples | · Mollusca
· Annelida · Some other protostomes |
· Echinodermata
· chordates |
| Cleavage type in humans | Not present in humans | Present in early stages of human embryonic development |