1. Animal Characteristics

2. Characteristics ► Eukaryotic ► Multicellular ► Ways of moving that help them reproduce, obtain food and protect themselves ► Have specialized cells that form tissues and organs ► Animal cells do not have cell walls

3. Characteristics ► Adults mostly fixed in size and shape ► Heterotrophic ► Must digest food

4. Development of Animals ► Most develop from single, fertilized egg call a _________________. ► Males produce _________, females produce ________. ► Fertilization occurs when an egg is penetrated by a sperm ► Fertilization may be internal or external

5. Development of Animals ► Unicellular zygote divides by mitosis ► Embryo develops until blastula formed ► Blastula develops into gastrula  Inner layer of cells called endoderm, develops digestive organs  Outer layer of cells called ectoderm, develops into skin and nervous tissue

6. Development of Animals ► Gastrula develops until mesoderm formed ► Mesoderm = muscles, circulatory, excretory system

7. Symmetry ► Asymmetry – no symmetry

8. Symmetry ► Radial – think equal slices of pie

9. Symmetry ► Bilateral – animals have anterior, posterior, dorsal and ventral surfaces

10. Posterior – butt, bottom Anterior – head, front Dorsal – back side Ventral – stomach side

12. Animal Protection and Support ► Exoskeleton or endoskeleton  Hard outer protection or inner skeleton to protect ► Invertebrates and vertebrates  Without backbone vs. with backbone