Chapter 31.1, Problem 1LO

Summary Introduction

To identify: The important characteristics of poriferans.

Concept introduction: All sponges belong to a phylum called Porifera. They are the simplest animals with cellular level of organization. They have diverged from other animals early in the evolution. Hence, they are called as basal animals. They have a very simple body structure composed of only two layers of cells. In between the two layers, a gelatinous region is present called mesohyl. The exchange of nutrient and waste material takes place through diffusion in sponges.