Do multicellular organisms develop, and if they do explain.

yes

Explanation:

Development in multi-cellular organisms happens in one of three ways

1) Number of cells increase

2) Size of existing cells increase

3) Both happen at the same time

1 ex -When you get a cut your existing cells replicate to heal the wound by simply replicating.

2 ex-There are sea slugs that consume plant life and then add the chloroplast to the existing cells on its back in order to create organic solar panels.

3 ex-When mammals are maturing the sexual systems both increase in size (increase in cell number) and become functional (development of new cell types through DNA sequences that were lying dormant)

thinking it would be physical characteristics