Why do you think biologists use both the embryological development and the adult body plans to classify an animal?

Question

My answer:
Biologists use both because there are many different phyla in the adult body plans. The embryological development help differentiate the classification.

Answer 1

Thats pretty close, if you think about it you can see the body development and what the animal gained in the adult body plans. Also how the animal started in the embryological development.