PORIFERA - PowerPoint PPT Presentation

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PORIFERA

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  1. PORIFERA Khuaten Maaneb de Macedoand Navdeep Singh

  2. Common Name: Sponges • Exclusively Aquatic • Approximately 15,000 Species Three Distinct Groups Glass Sponges (Class Hexactinellida) Calcareous Sponges (Class Calcarea) Demosponges (Class Demospongiae)

  3. Examples of Porifera Class Hexactinellida Class Calcarea Class Demospongiae

  4. Body Symmetry • Asymmetrical (no real body symmetry) • Radially Symmetrical

  5. Body Plan • Porifera lack true tissues • Two cell layers surrounding a Spongocoel. • Acoelomate • lack a coelom • is a fluid-filled body cavity located in the mesoderm • No formal digestive, circulatory, or nervous systems • Two layers: diplobalistic • endoderm • ectoderm

  6. Movement and Support System Adults Sessile No movement Anchored to Substrate Larvae Free Swimming Movement Support: Spicules comprise a skeletal Framework

  7. Nutrition Filter Feeders filter food out of the water Food Sources: bacteria plankton other tiny organic particles Flagellated Choanocytes move water Digestion: intracellular

  8. Gas Exchange Process • Diffusion through the membranes of cells • exterior of the cells absorb molecular oxygen and liberate carbon dioxide • Process • water through pores • canals that move water throughout sponge • oxygen from the water is used.

  9. Defense Mechanisms • Shed Spicules • Spicules: small, hard, • needlelike • supports the soft tissue Covered by Epibiotic Organisms Produce Toxins

  10. Excretion and Water Balance • Excretion: • water moves in and out through the pores • carbon dioxide and other wastes removed as water leaves • Water Circulation: • Water flow in through the pores • Water flow out through pores

  11. Reproduction • Hermaphrodites : • produces both sperm and egg cells. • Gametes arise form the choanocytes or amoebocytes, • eggs reside in the mesohyl • sperm are carried out of the sponge by the water current • cross fertilization Both Asexual and Sexual: Asexual :include fragmentation, budding, and gemmules • fertilized zygotes • flagellated • swim away from the parent sponge • settle on a suitable substrate, • develops into a sessile sponge Video: http://www.youtube.com/watch?v=KOFFzXNYJG0

  12. Response to Stimuli • No nervous tissues or systems • Response to stimuli: • chemically triggered from cell to cell • very slow

  13. PORIFERA ARE UNIQUE!!! • Asymmetrical • Sessile • Lack True Tissues • Porifera have choanocytes • choanocytes :responsible for moving water through the sponge