1. Chapter 31.2 Animals are a Diverse Classification

2. 31.2 The Traditional Classification of Animals The multicellular animals, or metozoans are traditionally broken into 35 phyla We can sort out which phyla are related by creating phlyogenies (Family trees) – Compares anatomical features and embryological development.

3. 31.2 The First Branch: Tissues Traditionally divided into 2 main branches 1. Parozoa – animals that lack a definite symmetry and posses neither tissue or organs (Mostly composed of the sponges: phyulum porifera) 2. Eumetozoa – animals that have a definite shape and symmetry and in most cases, tissues organized into organs and organ systems

4. 31.2 The Second Branch: Symmetry Eumetozoan branch of the animal family tree has 2 principle branches They differ in nature of the embryonic layers that form during development and go on to differentiate into the tissues of the adult animal

5. 31.2 The Second Branch: Symmetry Eumetozoans – 1.Radiata (having radial symmetry) have 2 layers, an outer ectoderm and an inner endoderm and are called diploblastic. 2.Bilateria (having bilateral symmetry) are triploblastic, produce a third layer, the mesoderm which is between the ectoderm and endoderm

6. 31.2 Further Branches Bilateral animals were split into 2 groups (with of body cavity and those without) Animals with a body cavity were split into 2 groups (those with a coelom and those without) Animals with a coelom were split into 2 groups (coelom derived from a digestive tube and those that did not)