1. Chapter 33 Notes
Invertebrates

2. Concept 33.1 Phylum porifera: - asymmetric - ex. sponges
- sessile adults, larva may swim
- have no nerves or muscles; individual cells can sense and react to environmental changes

3. Concept 33.1
- filter-feeders; choanocytes, or collar cells, ingest food filtered through the sponge
- most are hermaphrodites

4. Concept 33.1

5. Concept 33.1

6. Concept 33.2 Phylum Cnidaria: - radial symmetry
- ex. jellyfish, hydra, sea anemones, coral
- have stinging cells called nematocysts or cnidocysts; eject a barbed thread
- contain a gastrovascular cavity; single opening

7. Concept 33.2

8. Concept 33.2
- sessile forms are called polyp; free-floating are called medusa
- diploblastic (epidermis and gastrodermis); between layers is the mesogloea

9. Concept 33.2

10. Concept 33.2

11. Concept 33.2

12. Concept 33.2 There are 3 classes of Cnidarians: Hydrozoa:
- ex. hydra, Portuguese man-of-war
- most marine
- both polyp and medusa stages; polyp is often colonial

13. Concept 33.2 Scyphozoa: - ex. jellies - all marine
- polyp stage is reduced
- free-swimming

14. Concept 33.2

15. Concept 33.2 Anthozoa: - ex. sea anemones, coral - all marine
- medusa stage absent
- sessile

16. Concept 33.2

17. Concept 33.2 Phylum Ctenophora:
- means “comb-bearer” for the eight rows of fused cilia
- ex. comb jellies
- tentacles contain colloblasts to capture prey

18. Concept 33.3 Phylum Platyhelminthes:
- ex. Flatworms, flukes, tapeworms
- bilateral symmetry
- unsegmented
- triploblastic; acoelomates (no body cavity)

19. Concept 33.3 Class Turbellaria: - flatworms - free-living
- rely on diffusion for movement of food, oxygen, and waste
- asexual and sexual reproduction; can regenerate lost parts

20. Concept 33.3

21. Concept 33.3

22. Concept 33.3 Class Trematoda: - ex. blood flukes, liver flukes
- all parasitic: feed on veins/organs of host
- hermaphroditic

23. Concept 33.3 Class Cestoidea: - ex. tapeworms - all are parasites
- attach to intestinal wall with scolex and absorb food from host

24. Concept 33.3

25. Concept 33.3 Phylum Rotifera: - psuedocoelomates - freshwater
- complete digestive tract
- fluid in psuedocoelom acts as a hydrostatic skeleton

26. Concept 33.3

27. Concept 33.3 Phylum Nematoda: - ex. roundworms
- complete digestive system and closed circulatory system: blood is contained in vessels
- decomposers and parasites

28. Concept 33.4 Phylum Mollusca:
- ex. snails, slugs, clams, squids, octopuses
- body consists of three parts: foot, visceral mass, mantle
- open circulatory system
- gas exchange is via gills, lungs, or the body surface (diffusion)

29. Concept 33.4

30. Concept 33.4 Class Polyplacophora: - ex. chitons
- use foot to cling to rocks
- simple nervous system and sense organs

31. Concept 33.4

32. Concept 33.4 Class Gastropoda: - “stomach-foot” - ex. snails and slugs
- torsion: uneven growth in the visceral mass; rotates 180 degrees
- exchange gases via gills; use mantle cavity

33. Concept 33.4

34. Concept 33.4 Class Bivalvia: - “hatchet-foot”
- ex. clams, oysters, mussels
- foot used for motility or anchorage
- suspension feeders
- no distinct head

35. Concept 33.4

36. Concept 33.4 Class Cephalopoda: - “head-foot” - ex. squid and octopus
- carnivores; beak-like jaw to crush prey
- have chromatophores to allow them to change colors
- shell is reduced or absent

37. Concept 33.4

38. Concept 33.5 Phylum Annelida: - ex. earthworms, leeches
- all are segmented
- setae project from cuticle
- closed circulatory system; aortic arches

39. Concept 33.5
- developed nervous system with two ventral, solid nerve cords and cerebral ganglia
- complete digestive system: mouth-crop-gizzard-intestine-anus
- sexual and asexual reproduction
- tactile organs, chemoreceptors, balance receptors, and photoreceptors

40. Concept 33.5

41. Concept 33.5

42. Concept 33.5 Class Oligochaeta: - ex. earthworm - all have setae
- help aerate soil and cycle nutrients

43. Concept 33.5 Class Hirudinea: - ex. leeches - mostly freshwater
- either carnivorous or parasitic

44. Protosomia Class Polychaeta: - primarily marine
- parapodia with bristles; can be used for locomotion and gas exchange
- largest class

45. Protosomia