2. General Characteristics Multicellular No cell walls (bodies are held together by proteins such as collagen). Often contain specialized tissue such as nervous and muscle tissue. All are heterotrophic Often motile

3. Animal Bodies The bodies of most animals (all except sponges) are made up of cells organized into tissues. Each tissue is specialized to perform specific functions. In most animals, tissues are organized into even more specialized organs.

4. Radial vs. Bilateral symmetry Radial Can be divided into similar halves by more than two planes passing through it. Usually sessile, free- floating, or weakly swimming Primitive animals Cnidarians Echinoderms Bilateral Have a left and right side well-suited for directional movement Most animals

6. Cephalization Bilateral Symmetry usually has led to cephalization— the process by which sensory organs and appendages became localized in the head end of animals.

7. 3 Major Bilateral Body Plans 1.Acoelomates 2.Pseudocoelomates 3.Coelomates Each plan consists of 3 cell layers: 1.Endoderm 2.Mesoderm 3.Ectoderm

8. Acoelomates These animals have no other cavity than the gut. They are often called the “solid worms.”

9. Pseudocoelomates These animals have a body cavity (the pseudocoelom) which is not completely lined with mesoderm. The “tube within a tube” body plan. This category is also composed of mostly worms.

10. Coelomates These animals have a “true coelom” lined with mesodermal peritoneum. Most animals are coelomate.

11. Early development

12. Protostomes vs. Deuterostomes

14. Animal Numbers It is estimated that somewhere around 9 or 10 million species of animals inhabit the earth. About 800,000 species have been identified. These have been grouped into 36 separate phyla in the animal kingdom.

15. Porifera

16. Cnidaria

17. Platyhelminthes

18. Nematoda

19. Mollusca: Gastropoda

20. Mollusca: Pelycopoda

21. Mollusca: Cephalopoda

22. Annelida: Polychaeta

23. Annelida: Oligochaeta

24. Annelida: Hiridinea

25. Arthropoda: Crustacea

26. Arthropoda: Arachnida

27. Arthropoda: Chilopoda

28. Arthropoda: Diplopoda

29. Arthropoda: Insecta

30. Echinodermata: Crinoidea

31. Echinodermata: Astroidea

32. Echinodermata: Echinoidea

33. Echinodermata: Holothuroidea

34. Chordata: Subphylum Urochordata

35. Chordata: Subphylum Cephalochordata

36. Chordata: Subphylum Vertabrata Have a backbone Major classes: Agnatha Chondrichthyes Osteichthyes Amphibia Reptilia Aves Mamalia

37. Agnatha

38. Chondrichthyes

39. Osteichthyes

40. Amphibia

41. Reptilia

42. Aves

43. Mammalia