1. First Animals Soft bodies so trace fossils only Sponges Jelly fish
Worms
Late Proterozoic

2. Time Line of Animal Evolution
1st Fossil evidence of animals 570 mya = Proterozoic Eon
Massive adaptive radiation of animals called the Cambrian Explosion signaled the start of the Phanerozoic Eon
Cambrian Explosion due to
increased oxygen for aerobic respiration
more energy = larger more mobile animals
move into new areas and adapt

3. Phanerozioc begins with Cambrian Explosion

4. Evolution of Animals
Some type of Protist mutated to become multicellular
Multicellular organisms start as a single cell (zygote) and grow into organisms with groups of specialized cells performing different functions
All animals are multicellular

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

7. Proterospongia: Colonial, Unicellular Protists

8. Sponge collar cells

9. Phylum Porifera Sponges Only 3 types of cells Collar cells Amoebocytes
Epidermis cells
(protective outer layer of cells)
No tissues
Cells held together by jelly like substance
Skeleton make of proteins
Asymetrical

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

12. All other Animals have True Tissues & symmetry

13. Phylum Cnidaria Have stinging cells = cnidocytes Have tentacles
Radial symmetry = sit and wait predator
1st nervous system =
nerve net & eye spots

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

19. All other animals have Bilateral symmetry

20. Flatworms had it FIRST!!
Bilateral symmetry = evolved to facilitate directional motion = 1st mobile predator
Cephalization – development of a head
Ganglia: bundle of nerve cells make up a pre-brain
Nerves concentrated at ‘head end’ since sensory cells were concentrated at that end
Sensory nerves formed bundles = ganglion
Eyespots detect light, Auricles detect chemicals ‘smell’
2 nerve cords transmit info to rest of body

21. Evolution of Bilateral Symmetry

22. Flatworm primitive Traits
Central mouth and GVC

23. Free-living Flatworms = Class Turbellaria
Marine
Fresh-water

24. Flukes = Class Trematoda
Parasites of blood and liver

25. Swimmer’s Itch =Schistosoma

26. Tape Worms = Class Cestoda

27. Human Tape Worm Sources =Under cooked Prevention Beef (N. America)
Pork(S. America)
Fish (Asia)
Prevention
Cook your meat!!!

28. All Animals more advanced that flatworms have a body cavity
Provides room for organs to develop
Body Cavities are called coeloms

29. Types of body cavity (coelom)
Acoelomate Pseudocoelomate Coelomate

30. Round Worms = Phylum Nematoda
1st Animal with a body cavity =pseudocoelom
Fake body cavity – just a space between layers.