1. THE ENDOSYMBIOTIC THEORY Reduced carbon compounds + O 2 High ATP yield Electron transport Reduced carbon compounds Low ATP yield Fermentation Aerobic bacterium Anaerobic eukaryote chain Pyruvate and O 2 ATP 1. Eukaryotic cell surrounds and engulfs bacterium. 2. Bacterium lives within eukaryote cell. 3. Eukaryote supplies bacterium with reduced carbon compounds. Bacterium supplies eukaryote with ATP. Figure 27.12

2. The first animals (metazoans) They did not appear until about 600 million years ago But they rapidly radiated - the Cambrian explosion

3. Hallucigenia

4. Opabinia - Burgess Shale

6. Wiwaxia - Burgess Shale

8. Yohoia - Burgess Shale

9. Marrella - Burgess Shale

11. Anomalocaris - Burgess Shale

12. Choanoflagellata

13. Porifera - sponges

14. Collar cell of a sponge

15. Cnidaria - anemones

16. Cnidaria - jellyfish

17. Cnidaria - corals

18. Ctenophora - comb-jellies

19. Brachiopoda - lamp shells

20. Echinodermata

21. Hemichordata - acorn worms

22. Chordata - sea squirts, lancelets, vertebrates

23. Platyhelminthes - flatworms

24. Nemertea - ribbon worms

25. Mollusca

26. Annelida - segmented worms

27. Annelida - earthworm

28. Annelida - polychaetes

29. Arthropoda - arachnids

30. Arthropoda - crustaceans

31. Arthropoda - insects

32. Arthropoda - centipedes and millipedes (myriapods)

33. Onychophora - velvet worms

34. Nematoda - roundworms