Invertebrates

1. Invertebrates Chapter 33

2. Animal Origins

3. Animal Origins Animalia Choanoflagellates Diplomonadida Parabasala Euglenozoa Chlorophyta Rhodophyta Radiolaria Cercozoa Plantae Fungi Alveolata Stramenopila Amoebozoa Ancestral eukaryote Figure 28.4

4. Characteristics of the Animal Kingdom None of the following are unique to animals, but together distinguish animals from other organisms: Multicellular Heterotrophic No cell walls Motile during some stage(s) in life

5. Characteristics of the Animal Kingdom A great diversity of body plans occur; some key features include: Organized federation of cells vs. cells in tissues Tissue – integrated group of cells with a common structure and function Tissues are generally further integrated into organs Organs are generally further integrated into organ systems

6. Characteristics of the Animal Kingdom A great diversity of body plans occur; some key features include: For organisms with tissues: two vs. three principal embryonic tissues

7. Characteristics of the Animal Kingdom Two embryonic tissue layers: Blastocoel Zygote Blastula Blastocoel Endoderm Ectoderm Gastrulation Archenteron Blastopore Gastrula Fig. 32.2

8. Characteristics of the Animal Kingdom Two embryonic tissue layers: Endoderm – Innermost “germ layer”; differentiates into some of the internal tissues and the lining of most hollow organs, if these are present Ectoderm – Outermost “germ layer”; differentiates into tissues that cover the body and into the nervous tissues Blastocoel Endoderm Ectoderm Archenteron Blastopore Gastrula Fig. 32.2

9. Characteristics of the Animal Kingdom Three embryonic tissue layers: Fig. 32.9 Endoderm – Innermost “germ layer”; differentiates into some of the internal tissues and the lining of most hollow organs, if these are present Mesoderm – Middle “germ layer”; differentiates into muscles, circulatory and skeletal systems, and sex organs, if these are present Ectoderm – Outermost “germ layer”; differentiates into tissues that cover the body and into the nerve tissues

10. Characteristics of the Animal Kingdom A great diversity of body plans occur; some key features include: Radial vs. bilateral symmetry Fig. 32.7 A single midline plane produces roughly mirror-image halves; generally accompanied by distinct cephalization Any plane that passes through the central axis produces roughly mirror-image halves

11. Characteristics of the Animal Kingdom A great diversity of body plans occur; some key features include: Among organisms with 3 germ layers:Acoelomate, pseudocoelomate, or coelomate

12. Characteristics of the Animal Kingdom A great diversity of body plans occur; some key features include: Among organisms with 3 germ layers:Acoelomate, pseudocoelomate, or coelomate Fig. 32.8 Acoelomate: lack a coelom, i.e., lack a body cavity between digestive track and body wall

13. Characteristics of the Animal Kingdom A great diversity of body plans occur; some key features include: Among organisms with 3 germ layers:Acoelomate, pseudocoelomate, or coelomate Fig. 32.8 Pseudocoelomate: Fluid-filled body cavity between digestive tract and body wall partially lined by mesoderm

14. Characteristics of the Animal Kingdom A great diversity of body plans occur; some key features include: Among organisms with 3 germ layers:Acoelomate, pseudocoelomate, or coelomate Fig. 32.8 Coelomate: fluid-filled body cavity between digestive tract and body wall completely lined by mesoderm

15. Characteristics of the Animal Kingdom A great diversity of body plans occur; some key features include: Protostome vs. deuterostome development

16. Characteristics of the Animal Kingdom A great diversity of body plans occur; some key features include: Protostome vs. deuterostome development See Fig. 32.9

17. Cnidaria Chordata Mollusca Annelida Rotifera Silicarea Phoronida Nemertea Calcarea Arthropoda Ectoprocta Ctenophora Brachiopoda Nematoda Echinodermata Platyhelminthes “Radiata” Deuterostomia Lophotrochozoa “Porifera” Ecdysozoa Bilateria Eumetazoa Metazoa Ancestral colonial flagellate The Animal Kingdom ~ 35 phyla Fig. 32.11&Table 33.7

18. Porifera Cnidaria Chordata Echinodermata Other bilaterians (including Nematoda, Arthropoda, Mollusca, and Annelida) Deuterostomia Bilateria Eumetazoa Ancestral colonial choanoflagellate Phylum Porifera – Sponges Figure 33.2

19. Phylum Porifera – Sponges Organized aggregation of cells Probably the most similar extant group to the protistan colonial precursors to the animals

20. Phylum Porifera – Sponges Organized aggregation of cells Three main cell types, but no true tissues Asymmetric body plan Mostly marine, but some inhabit fresh water

21. Phylum Porifera – Sponges Internal skeleton of protein spicules E.g., natural bath sponge

22. Porifera Cnidaria Chordata Echinodermata Other bilaterians (including Nematoda, Arthropoda, Mollusca, and Annelida) Deuterostomia Bilateria Eumetazoa Ancestral colonial choanoflagellate Eumetazoa All animals except sponges belong to the clade Eumetazoa All eumetazoans have true tissues Figure 33.2

23. Phylum Cnidaria – Corals, Jellyfish, Anemones Radially symmetric animals with 2 germ layers (true tissues), but generally lacking true organs Rudimentary nerve net and contractile tissue Gastrovascular cavity; mouth and anus are the same opening

24. Phylum Cnidaria – Corals, Jellyfish, Anemones Tentacles contain cnidocytes Fig. 33.6

25. Phylum Cnidaria – Corals, Jellyfish, Anemones Polyp and medusa forms Fig. 33.5

26. Phylum Cnidaria – Corals, Jellyfish, Anemones Polyp and medusa forms

27. Phylum Ctenophora – Comb jellies 8 rows of comblike plates of cilia

28. Porifera Cnidaria Chordata Echinodermata Other bilaterians (including Nematoda, Arthropoda, Mollusca, and Annelida) Deuterostomia Bilateria Eumetazoa Ancestral colonial choanoflagellate Bilateria Bilaterally symmetric, cephalized animals with 3 germ layers Figure 33.2

29. P. Platyhelminthes – Flat worms Gastrovascular cavity (if a gut is present) Some true organs are present (tissues grouped into functional structures) Hermaphroditic and capable of self-fertilization Acoelomate

30. P. Platyhelminthes – Flat worms Mostly free-living

31. P. Platyhelminthes – Flat worms Mostly free-living Some parasitic E.g., tapeworms

32. P. Rotifera – Rotifers Distinguishing feature is a “crown of cilia” around the mouth Complete digestive tract surrounded by pseudocoelom Parthenogenesis (development from unfertilized eggs) is the most common mode of reproduction

33. P. EctoproctaP. PhoronidaP. Brachiopoda All bear a lophophore – fold of the body wall bearing ciliated tentacles surrounding the mouth Coelomate

34. P. Ectoprocta a.k.a. bryozoans Colonial Many contribute to marine reefs

35. P. Phoronida A group of tube-dwelling marine worms

36. P. Brachiopoda a.k.a. lamp shells Marine, mostly extinct

37. P. Nemertea a.k.a. proboscis or ribbon worms Structurally acoelomate, with a small fluid-filled sac that may be a vestigial coelom Closed circulatory system, but no heart

38. P. Mollusca a.k.a. mollusks

39. P. Mollusca a.k.a. mollusks Coelomate body with a muscular foot, visceral mass, and mantle (which secretes a shell in many species)

40. P. Mollusca a.k.a. mollusks 8 classes, including: C. Polyplacophora (chitons) Shell divided into 8 plates

41. P. Mollusca a.k.a. mollusks 8 classes, including: C. Gastropoda (snails and slugs) Single shell or lacking shell

42. P. Mollusca a.k.a. mollusks 8 classes, including: C. Gastropoda (snails and slugs) Single shell or lacking shell

43. P. Mollusca a.k.a. mollusks 8 classes, including: C. Bivalvia (clams, oysters, mussels, etc.) Hinged, two-part shell

44. P. Mollusca a.k.a. mollusks 8 classes, including: C. Cephalopoda (squids, octopuses, nautiluses) Only mollusks with closed circ. system and complex brain

45. P. Mollusca a.k.a. mollusks 8 classes, including: C. Cephalopoda (squids, octopuses, nautiluses) Only mollusks with closed circ. system and complex brain

46. P. Annelida a.k.a. segmented worms

47. P. Annelida a.k.a. segmented worms Segmented Coelomate Coelom Closed circulatory system

48. P. Annelida a.k.a. segmented worms 3 classes: C. Oligochaeta Earthworms and their kin Coelom

49. P. Annelida a.k.a. segmented worms 3 classes: C. Polychaeta Bristled parapodia on each segment

50. P. Annelida a.k.a. segmented worms 3 classes: C. Hirudinea Leeches