1. Evolution of Animals
Some type of Protist mutated to become multicellular instead of colonial
Colonial cells live together but can survive if separated from the colony
Cells of multicellular organisms CAN NOT live if removed from the other cells
All animals are multicellular

3. Proterospongia = Protist & common ancestor to all animals?

4. Proterospongia: Colonial, Unicellular Protists

5. Sponge choanocytes (collar cells)

6. Phylum Porifera Sponges 3 types of cells No tissues
Collar cells (choanocytes)
Amoebocytes
Epidermis cells (protective outer layer of cells)
No tissues
Cells held together by mesohyle (jelly)
Skeleton of spicules & spongin protein

8. Intracelluar digestion
Collar cells take in food by endocytosis
Food digested in food vacuoles
Some food passed to amoebocytes
Amoebocytes carry food around sponge body. (circulaton)

9. Other Porifera Traits Asymmetrical = no symmetry
Respiration by diffusion
Excretion by diffusion
Reproduction = male gametes released into water, filtered out of water by another sponge. Female gametes stay in mesohyle until fertilized. Zygote grows into a swimming larva.
Larva settles to ground & becomes sessile adult

10. Eumetazoa = Animals with True Tissues

11. Phylum Cnidaria Have stinging cells = cnidocytes Have tentacles
Have myocytes = muscle like cells that contract
1st predatory animals
Have Radial symmetry =sit and wait predator
1st nervous system = nerve net & eye spots

13. Digestion & Circulation
Have gastrovascular cavity for digestion & circulation
1st extra cellular digestion – cells lining GVC secrete digestive enzymes into GVC to digest food
Evolutionary advantage = can eat larger food
Cillia lining GVC push digested food particles around the body
GVC branches into all tentacles: comes near all cells

15. Respiration & Excretion
Respiration by diffusion
Excretion by diffusion
Both are possible since entire body is only a few cell layers away from external water

16. Reproduction = complex life cycle
Medusa = swimming
Polyp = sessile
Medusa =sexual
Egg & sperm
External fertilizaion
Polyp = asexual
budding