How does Cnidaria fit in?

1. How does Cnidaria fit in? Cnidaria 3 classes:Hydrozoa, Scyphozoa, Anthozoa Porifera 2 body types: polyp, medusa diploblastic 3 body types tissue level of organization choanocytes cellular level of organization Blastula stage heterotrophic multicellular unknown common ancestor eukaryote

2. How do the Acoelomates fit in? the acoelomates Platyhelminthes Nemertea Cnidaria Porifera unknown common ancestor

3. The Acoelomates

4. Acoelomate Characteristics Organ level of organization Tissues are organized to for organs which are used to accomplish physiological functions

5. Acoelomate Characteristics Triploblastic 3 Tissue Layers gastrodermis mesoderm epidermis 3 Embryonic Germ Layers endoderm mesoderm ectoderm

6. Acoelomate Characteristics No body cavity ectoderm ectoderm mesoderm mesoderm Gut endoderm endoderm

7. Acoelomate Characteristics Triploblastic Mesoderm (mesenchyme, parenchyma) Gut Ectoderm Endoderm

8. Acoelomate Characteristics Bilateral Symmetry Anterior: toward the front of the body Posterior: toward the rear of the body

9. Acoelomate Characteristics Cephalization the concentration of sensory organs in the head of the animal Eye spots Auricles

10. Phylum Platyhelminthes the flatworms

11. Physiology Feeding • Free-living, carnivorous • parasitic Digestion • intestine is simple or branched • incomplete system (no anus) • digestive system reduced or absent in parasitic species

12. Physiology Osmoregulation and excretion • Protonephridia and flame cells • much excretion is via diffusion protonephridia flame cell

13. Physiology Cerebral ganglia Nervous system -ladder-like -cephalization -nervous system is reduced in parasitic species Lateral nerve cords Skeletal and circulatory systems • absent

14. Physiology Reproduction Asexual Sexual • usually monoecious, but most must cross fertilize • Internal fertilization (usually reciprocal)

15. Phylum Platyhelminthes Class Turbellaria Class Trematoda Class Cestoda

16. Class Turbellaria • Free-living flatworms • move on slime trails using cilia

17. Class Turbellaria • predatory • use a pharynx to capture prey pharynx

18. Class Turbellaria • have a branched (or lobed) gut

19. ClassTurbellaria Reproduction Asexual • Fission

20. ClassTurbellaria Reproduction Sexual • internal fertilization • simple life cycle

21. Adaptations for Parasitism • increased reproductive potential • monoecious • presence of adhesion organs (suckers, hooks) • poorly developed sensory systems • reduced, or absent, digestive system • resistant cuticle • complex life cycles with more than 1 host

22. Class Trematoda • Parasitic Flukes • endoparasitic

23. Trematoda Life Cycle • have at least two hosts in their life cycle • final host = vertebrate Vertebrate host #1 infective stage in host muscle Vertebrate host #2 adult fluke (in host liver) Invertebrate host eats eggs

24. Class Cestoda Parasitic tapeworms

25. Class Cestoda 2 body regions: scolex and proglottids scolex proglottids

26. Class Cestoda Scolex suckers rostellum

27. Class Cestoda • Proglottids • repeating segments containing reproductive organs • may be immature, mature, or gravid

28. Class Cestoda Immature proglottids • found at the anterior end of the tapeworm • contain no noticeable sex organs

29. Class Cestoda Mature proglottids • found in the middle of the tapeworm • contain noticeable sex organs • sperm must come from either a different proglottid or a different individual

30. Class Cestoda genital pore Mature proglottids sperm duct vagina uterus ovary testes

31. Class Cestoda Gravid proglottids • found at the posterior end of the tapeworm • contain fertilized eggs • entire proglottid is shed in the host’s feces uterus eggs

32. Cestoda Life Cycle Adult tapeworm (in host intestine) Gravid proglottids Vertebrate host #2 Infective stage in host muscle eggs Vertebrate host #1

33. Ecology • Parasitic flatworms infect many people in some parts of the world (for example, the Chinese liver fluke infects approx. 30 million people in Asia) • Some Trematodes have display polyembyony: a single larvae can have up to 4 younger larvae developing within it • Trematodes are a model system for studying host parasite coevolution

34. Phylum Nemertea the ribbonworms

35. Physiology Feeding • Free-living, carnivorous • have an eversible proboscis that is not connected to the digestive system • Proboscis is used to stab prey and may have a poisonous tip (or stylet)

36. Physiology rhynchocoel proboscis mouth rhynchocoel

37. Physiology Digestion • intestine is unbranched • complete system (mouth and anus) This is the first animal to have an anus!!!

38. Physiology Reproduction Asexual • Some species are capable of reproducing asexually through fragmentation and regeneration • Sexual • usually dioecious • internal fertilization

39. Physiology Osmoregulation and excretion • same as Platyhelminthes Nervous system • same as Platyhelminthes Skeletal system same as Platyhelminthes

40. Physiology Circulation • closed circulatory system consisting of contractile blood vessels This is the first animal to have a closed circulatory system!!!

41. Ecology • Nemerteans are mostly marine, although there are a few species found in freshwater (and even a few on land!) • They range in size from a few millimeters to 30 meters • Their biology is little known in part because they are extremely fragile and fragment easily

42. How do the acoelomates fit in? Nemertea Platyhelminthes acoelomate Complete digestive system acoelomate Closed circ. system Ladder-like nervous system Cnidaria proboscis Porifera cephalization protonephridia organ level of organization triploblastic unknown common ancestor