Porifera

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Porifera

  1. 1. Porifera
  2. 4. Pseudocoelomate
  3. 5. Core Concepts <ul><li>Poriferans are commonly referred to as sponges. An early branching event in the history of animals separated the sponges from other metazoans. Fossil sponges are among the oldest known animal fossils, dating from the late Precambrian. The number of described fossil genera exceeds 900. </li></ul>
  4. 6. <ul><li>The approximately 5000+ living sponge species are classified in the phylum Porifera, which is composed of three distinct groups namely: Hexactinellida (glass sponge), Demospongia (common sponge), and Calcarea (calcareous sponge). </li></ul><ul><li>  </li></ul>
  5. 7. <ul><li>They are the most complex invertebrate and the simplest among animals. In terms of habitat, 100+ out of 5000+ are capable of living in freshwater environment. This group seems to have no known enemies or predators. </li></ul>
  6. 8. Porifera <ul><li>Porifera ostium/ia osculum/a </li></ul><ul><li>Spicule spongin budding </li></ul><ul><li>Hermaphrodite archaeocytes sclerocytes </li></ul><ul><li>Porocytes pinacocytes choanocytes/collar cells </li></ul><ul><li>Spongocytes spongocoel holdfast </li></ul><ul><li>Metazoans unidirectional spongocoel </li></ul><ul><li>Mesenchyme choanoflagellates Hexactinellida </li></ul><ul><li>Demosponge Calcareous gemmules </li></ul><ul><li>Buds collagen </li></ul>
  7. 9. Feeding <ul><li>Lack mouth; presence of osculum/ostium </li></ul><ul><li>Unidirectional flow of water </li></ul><ul><li>Choanocytes cause movement of water within the spongocoel </li></ul><ul><ul><li>How? </li></ul></ul><ul><li>Still some of them harbor symbionts like green algae, and dinoflagellates </li></ul>
  8. 11. Skeleton <ul><li>Used to differentiate poriferans </li></ul><ul><ul><li>Spicules </li></ul></ul><ul><ul><li>. Poriferans have diverse skeletal elements including calcareous laminae, organic filaments, and siliceous and calcareous spicules. </li></ul></ul><ul><ul><li>Also used to determine evolutionary relationship </li></ul></ul>
  9. 12. Cellular organization <ul><li>  do not have organs </li></ul><ul><li>Five basic cell types </li></ul><ul><ul><li>archaeocytes (totipotent cells, can be gametic cells, can be digesting cells) </li></ul></ul><ul><ul><li>sclerocytes (produces spicules) </li></ul></ul><ul><ul><li>pinacocytes (skin cells) </li></ul></ul><ul><ul><li>porocytes (pore cells that minimally contracts) </li></ul></ul><ul><ul><li>collar cells or chaonocytes (with beating flagella and food trapping device). </li></ul></ul><ul><li>  </li></ul>
  10. 13. Reproduction <ul><li>Reproduce both asexually and sexually </li></ul><ul><li>MOST are hermaphroditic in the sense that each produces sperms and eggs at different times. </li></ul><ul><li>Mesenchyme (mesohyl)- site of fertilization </li></ul><ul><li>ggSponges that reproduce asexually produce buds, or more often, gemmules, which are packets of several cells of various types. </li></ul>
  11. 14. Gemmule

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