Chapter 30.5, Problem 2R

Summary Introduction

To review:

The reasons for considering sponges and placozoans as animals.

Introduction:

Sponges belong to phylum Porifera and are diploblastic, multicellular, and simple animals, while placozoans are flat, multicellular, and diploblastic organisms. Both of these two phyla are considered to be primitive animal forms and represent the sister group of the metazoan clade in the animal evolution tree.