Question

In which group of bilaterians do you find solid bauplan? Why is it called so?

Answer 1

I think this answer is correct

Answer 2

Bauplan or ground plan is a set of morphological features common to many members of a phylum of animals. Platyhelminthes is the group of bilaterians with solid bauplan. Body cavity is absent in these animals. In these animals, the mesenchyme derived from the third germinal layer, mesoderm occupies the entire blastocoels between the ectoderm and endoderm. As there is no body cavity, the acoelomates exhibit solid body plan.