Review: Evolution of Life First life on Earth are prokaryotes (bacteria) Endosymbiosis gives rise to eukaryotes (protists) Photosynthetic protists give rise to plants Aquatic, single-celled flagellated protists give rise to fungus Fungus gives rise to animals

KINGDOM ANIMALIA Multicellular eukaryotes that ingest their food

Characteristics of Animals All animals share certain characteristics: – Multicellular eukaryotes – Heterotrophic  ingest their food Ingestion – take food into body, digest internally Carnivores, herbivores, omniovores, detritivores

Characteristics of Animals, cont. Most reproduce sexually Development:

How are animals classified? Four key characteristics for classification  Body Plan 1.Symmetry 2.Tissues 3.Body cavities 4.Pattern of development

1. Symmetry 3 types:

2. Tissues Presence of true tissues – Group of similar cells that work together to perform a specific function Form from germ layers during development – Ectoderm: covers surface – Endoderm: innermost germ layer – Mesoderm: fills space between ectoderm and endoderm Animals can be: – Diploblastic (“two layered”) or – Triploblastic (“three layered”)

3. Body Cavities Coelom = fluid-filled space separating the digestive tract from the outer body wall Digestive Cavity Body Cavity Digestive Tract Outer Body Wall

3. Body Cavities, cont. Three types of body cavities: 1.Acoelomate (“lacking cavity”) – No body cavity  solid body, space filled with mesoderm 2.Pseudocoelomate (“false cavity”) – Cavity forms between mesoderm and endoderm 3.Coelomate – Cavity forms within the mesoderm

4. Pattern of Development Protostome or deuterostome depending on cell cleavage and fate, coelom formation, and fate of blastophore ProtostomeDeuterostome 1. Cell cleavageSpiralRadial 2. Cell fateDeterminateIndeterminate 3. Fate of blastophoreMouthAnus 4. Coelom formationMesoderm splitsMesodermal outpocketings