| Organisms | Characteristics |
| Platyhelminthes | They are triploblastic, acoelomates having bilateral symmetry with the incomplete digestive system. |
| Echinoderms | Adults show pentaradial symmetry, while the embryonic show bilateral symmetry. The mode of embryonic development is indirect. |
| Hemichordates | They are triploblastic, coelomates having cylindrical bodies with no segmentation |
| Aves | Aves and mammals have a four-chambered heart, that prevents the mixing of oxygenated and deoxygenated blood and hence are warm-blooded. The mode of embryonic development is direct. |