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Simple Invertebrates Sponges, Cnidarians, Flatworms, Roundworms

Simple Invertebrates Sponges, Cnidarians, Flatworms, Roundworms. Chapter 23.3. Sponges. Sponges. Unlike other animals Once classified as plants Sessile Don’t move Attached Lack symmetry Lack tissues. Favorite Sponges. What is wrong with the image?. Sponge Size. Varies

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Simple Invertebrates Sponges, Cnidarians, Flatworms, Roundworms

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  1. Simple InvertebratesSponges, Cnidarians, Flatworms, Roundworms Chapter 23.3

  2. Sponges

  3. Sponges • Unlike other animals • Once classified as plants • Sessile • Don’t move • Attached • Lack symmetry • Lack tissues

  4. Favorite Sponges • What is wrong with the image?

  5. Sponge Size • Varies • Depends on current velocity and space • Encrusting sponges • Small (< 1 cm dia.) • Upright sponges • Larger ( 2 m dia.)

  6. Sponge Classification • Phylum Porifera • “Pore bearer” • Ostia • Many small openings • Water enters • Cover body • Oscula • Larger openings • Water exits

  7. Sponges • All aquatic • Few freshwater species • Most marine • Most bag-shaped • Large internal cavity • All filter feeders • Pump water through body • Filter small particles from water

  8. Sponge Bodies • Simplest animals • No tissues • Only two cell layers • Jellylike substance around cells = mesohyl • Cell recognition

  9. Sponge Cells • Perform all functions • Four types: • Epithelial cells • Choanocytes • Amoebocytes • Porocytes

  10. Sponge Cell Layers spicule mesohyl • two cell layers thick with a connective tissue layer in between, the mesohyl (dark blue pattern) pinaco- cytes • The outer layer composed of pinacocytes (eipthelial layer in lab) (baby blue) amebo- cytes - The inner layer are the choanocytes (peach, black). choanocytes • Mesohyl which contains spicules, amebocytes, etc… EXTERIOR | INTERIOR

  11. Filter Feeding • Choanocytes • “Collar cells” • Line central cavity • Spongocoel • Flagellated • Create currents

  12. Filter Feeding • Choanocytes • Act as sieves • Trap plankton • Pulled into cell • Digested intracellularly • Wastes expelled

  13. Epithelial Cells • Epithelial cells • Thin and flat • Surface cells • Pinacocytes • Respond to touch and chemicals • Can close pores

  14. Simple Digestion • Digested within the cell • Nutrients released into mesohyl • Middle layer • Contains spicules and amoebocytes

  15. Amoebocytes • Amoeba-shaped cells • Blob-like • Move like an amoeba • Between cell layers of sponge • Function to carry nutrients to other cells • Carry away wastes • Aid in reproduction • Produce chemicals to make spicules

  16. Pore Cells • Porocytes • Megaphone shaped • Single cell around each pore • Create the openings • Can close • Regulate water flow • sponge feeding 5:22

  17. Sponge Skeletons • Provides framework and support • Gives general shape • Used to classify • Made of: • Calcium carbonate • Silica • Protein = spongin

  18. Spicules • Not cells – not living • Small needle-like structures • Composed of silica or calcium • Located between cell layers in mesohyl • Function in support • Produced by other cells

  19. Spongin • Protein • Tough fibrous network • Flexible • Skeleton of bath sponges

  20. Review Structure

  21. Sponge Body Wall

  22. Feeding Review

  23. Diversity of Sponges • Three classes: • 1) Demosponges • 2) Calcareous sponges • 3) Hexactinellida

  24. Classes of Sponges • 1) Class Demospongiae • Largest goup • Ninty percent • Bath sponges • No spicules – just spongin • Soft to the touch

  25. Classes of Sponges • 2) Class Calcarea • Most primative • Shallow water species • Spicules of calcium carbonate • Hard • “rock sponges”

  26. Classes of Sponges • 3) Class Hexactinellida • Small group • Skeletons of silicon oxides • “Glass sponges" • Deep-water forms • Ex: Venus'-flower-basket • In Japan Venus'-flower-baskets • Given as wedding presents to symbolize lifelong devotion and fidelity

  27. Classification of Sponges • Based on canal systems: • Asconoid • Syconoid • Leuconoid

  28. Sponge Reproduction • Asexual • Regeneration • Cut pieces grow into new sponges • Budding • Copies grow off original

  29. Asexual Reproduction • Gemmules • Freshwater sponges • Encased amoebocyte cells • Withstand drought or freezing • Hatch to form new sponges

  30. Sponge Reproduction • Sexual • Also common • Most are hermaphrodites • Produce both egg and sperm • Different times to avoid self-fertilization • Spawning

  31. Sponge Reproduction • Fertilization • Sperm released • Moves through water and enters pore • Collar cells pass it to mesohyl • Fertilizes egg here

  32. Sponge Development • Fertilized egg develops into larva • Brief free-swimming stage • Attaches and grows into sponge

  33. Sponges and Humans • Bath sponges • Harvested for our use • Biomedical compounds • Have antimitotic properties • Stunt growth of cancer cells • Indicators of environmental health • WI distribution is down

  34. Cnidarians

  35. Cnidarian Classification • Domain = Eukarya • Kingdom = Animalia • Phylum = Cnidaria • Four classes: • Hydrozoa • Scyphozoa • Anthozoa • Cubozoa (box jellies)

  36. Cnidarians • Simple animals • More advanced than sponges • Have specialized tissues • Two layers of cells • Ectoderm • Endoderm • Middle layer of mesoglea

  37. Cnidarian Characteristics • Tissue layers = 2 • No organs • Radial symmetry • Cnidocytes • Tentacles • Feeding and grasping • Extracellular digestion

  38. Cnidarian Body Forms • Two basic types: • Medusa • Free floating • Umbrella-shaped • Mouth below • Tentacles hang down • Polyp • Attached • Vase-shaped • Mouth upward • Tentacles upward

  39. Body Forms

  40. Cnidocytes • Stinging Cells • Distinguishing trait • Cnidaria • From Greek “cnidos” = Stinging nettle • Contain nematocysts • Small barbed harpoon • Explode forcefully • May contain toxins

  41. Cnidocyte Function

  42. Extracellular Digestion • Outside cell • Food can be larger than cell • Gastrovascular cavity • Central cavity • Breaks food down • One opening

  43. Recall Cnidarian Classification: • Domain = Eukarya • Kingdom = Animalia • Phylum = Cnidaria • Four classes: • Hydrozoa • Scyphozoa • Anthozoa • Cubozoa (box jellies)

  44. 1) Class Hydrozoa • Most primitive cnidarians • Most are colonial and marine • Polyp and medusa stages

  45. Ex: Hydra • Freshwater • Unique • No medusa stage • Attach by basal disk • Reproduce asexually or sexually • Studied in schools

  46. Hydra Anatomy

  47. Hydra Anatomy

  48. Hydra Feeding • Hydra in pond water • Hydra feeding

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