Body Symmetry & Coelomate

1. Body Symmetry&Coelomate

2. Symmetrical

3. Acoelomateno mesoderm

4. Pseudocoelomatemesoderm attach to one side but no cleavage

5. Coelomatemesoderm cleavage with coelom inbetween

6. Segmented Body

7. Porifera (spongy) Asymmetric body Lack of body organizaiton

8. Structure Spicules as structural component Choanocyte for water flow and feeding

9. Adaptive features

11. Coelenterata & Platyhelminthes

13. Introduction to coelenterata • Radially symmetrical • Diploblastic • With nematocysts for food capture and protection

14. No blood, respiratory, or excretory organs • A network of nerve cells and fibres exists in body wall • Single internal cavity with only opening to the exterior, the ‘mouth’ which is surrounded by tentacles • Reproduction by assexual budding in polyp stage, sexual reproduction by eggs and sperm in medusa stage

15. Polyp and Medusa • Polyp • body is tubular or cylindrical • oral end, bering the mouth and tentacles, is directed upwards, and the opposite, or aboral end is attached • layer of mesoglea is thin

16. Polyp

17. Medusa • body resembles a bell or umbrella, with the convex side upward and the mouth located in the cneter of the concave under-surface • tentacles hang downwards from the margin of the ‘bell’ • layer of mesoglea is extremely thick

18. Medusa

19. Adaptive features

21. Nematoblasts • Nematoblasts • they are in the ectoderm • each consists of highly complex organelle, nematocyst, which is a minute capsule filled with fluid and containing a coiled, barbed thread tube

23. when the triggering device, cnidocil, on the outer surface of the nematoblast is stimulated, the thread tube everts to aid in capture of prey, protection or locomotion

24. Morphology of Obelia • Classification • Class Hydrozoa (hydroids) • Habitat • lives in shallow coastal water attached to substratum • Morphology • exists in 2distinctly different forms in its life • colonial form (polyps) • free living form (medusa)

25. The colonial form

26. Medusa

28. Sea Anemone

29. Introduction to Platyhelminthes • Triploblastic, bilaterally symmetrical, acoelomate and unsegmented • Body is flattened dorsoventrally • Digestive system incomplete –a mouth but no anus • No skeletal, circulatory, or respiratory systems; excretory system of many flame cells joined to excretory ducts

30. Nervous system primitively a simple nerve net, but advanced forms have a pair of anterior ganglia or a nerve ring and 1 to3 pairs of longitudinal nerve cords with transverse connectives • Complex hermaphroditic reproductive system; internal fertilization; development either direct or with 1 or more larval stages

31. Adaptive features

33. Planaria • Habitat • the common planaria inhabit cool ,clear permanent lakes and streams, where they avoid light by clinging to the under surface of stones or logs in the water

34. Structure

36. Cross section of body

38. Tapeworm • Habitat • The adult stage lives in the small of its primary host (e.g. man) i.e. it is an endoparasite • The immature stage lives inside the body of the secondary host (e.g. pig)

39. Structure

41. Life Cycle

42. In Human Intestine In Human Intestine To Soil In Pig Muscle

44. Nematoda

46. Adaptive features

47. Annelids & Arthropods

48. External view of an earthworm

49. Introduction to annelids • Annelids…for example as earthworm • belong to the Phylum Annelida • are segmented worms showing metameric segmentation • are coleomate animals • have a fluid-filled body in which the gut and other organs are suspended • are further classified into three classes: polychaeta, oligochaeta, hirudinea

50. Body structure ofannelids • enlarged coelom to accommodate more complex internal organs. • well-developed, fluid-filled coelom and the tough integument act as a hydrostatic skeleton. • Closed circulatory system with blood vessels running the length of the body and branching into every segment