Final answer:
Organisms that are radially symmetrical have two embryonic germ layers: the endoderm and ectoderm. These layers form the wall of the digestive tract and cover the surface of the animal.
Step-by-step explanation:
Organisms that are radially symmetrical have two embryonic germ layers. These layers are the endoderm and ectoderm. The endoderm forms the wall of the digestive tract, while the ectoderm covers the surface of the animal. Animals that display radial symmetry are called diploblasts and have a non-living middle layer between the endoderm and ectoderm.