What are the 3 germ layers of an animal embryo and what does each give rise to? and....?

Question

Which animal phylum has only 2 of these germ areas?

Answer 1

Triplobalstica (have 3 germ layers)

the three germ layers are

1) ectoderm the outer layer give rise to the epidermis of the skin , hairs ,nails ,sweat galnds, brain ,spinal cord, nerve ganglia , nerves , sensory organs ,lens of the eye ,cornea , lining of mouth , nostrils and a**s , enamel of teeth

2) mesoderm the middle layer Give rise to mucsles ( smooth skeletal and cardiac ) dermis of the skin , connective tissue, bone , cartilage ,dentine of teeth , blood and blood vessels , mesentries , kidney , testes and ovaries

3) endoderm the inner layer Give rise to lining of the gut , lining of respiratory tracts ( trachae, bronchi and lungs ) liver , pancreas , lining of gall bladder , thyroid , parathyroid , thymus gland , urinary bladder and linig of urethra.

Diploblasty is a condition in which there are two primary germ layers: the ectoderm and endoderm

include cnidaria and ctenophora

Answer 2

Endoderm: The endoderm forms: the stomach, the colon, the liver, the pancreas, the urinary bladder, the lining of the urethra, the epithelial parts of trachea, the lungs, the pharynx, the thyroid, the parathyroid, and the intestines.

Mesoderm: The mesoderm forms: skeletal muscle, the skeleton, the dermis of skin, the crystal lens of the eye, connective tissue, the urogenital system, the heart, blood (lymph cells), and the spleen.

Ectoderm: The ectoderm forms: the central nervous system, the lens of the eye, cranial and sensory, the ganglia and nerves, pigment cells, head connective tissues, the epidermis, hair, and mammary glands.

Cnidarians has only two of these germ layers - ectoderm and endoderm