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Phylum Porifera

Phylum Porifera. General Characteristics. SPONGES ! Simplest of all animals Cellular level organization Specialized cells, but no tissues (bodies are a loose aggregation of cells) No true tissues or organs Radial or asymmetrical Marine and Freshwater Saltwater are colorful

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Phylum Porifera

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  1. Phylum Porifera

  2. General Characteristics • SPONGES! • Simplest of all animals • Cellular level organization • Specialized cells, but no tissues (bodies are a loose aggregation of cells) • No true tissues or organs • Radial or asymmetrical • Marine and Freshwater • Saltwater are colorful • Freshwater are dull green color

  3. General Characteristics Cont. • Sponges are sessile (not free moving) as adults • Free swimming larval stage called dipleurula • Porifera means pore-bearing • Water enters through pores (ostia) bringing in food and oxygen • Sexual & Asexual Reproduction • Osculum- large opening at the top where excess water leaves

  4. Water Flow Through the Sponge WATER OUT WATER IN Osculum

  5. 3 Basic Cell Types • Pinacocytes • Mesenchyme Cells • Choanocytes

  6. 3 Basic Cell Types • 1. Pinacocytes- flat cells that line the outer surface of the sponge. • May be slightly contractile • Porocyte: a specialized type of pinacocyte; are tube-like in shape; contractile; and can regulate water circulation.

  7. 2. Mesenchyme Cells- move around in the mesohyl layer; are specialized for reproduction, secreting the skeleton, transporting/storing food. • Amoebocyte: jelly-like layer just underneath the pinacocyte layer. (makes spicules – skeletal)

  8. 3. Choanocytes- flagellated cells that line the inner chamber of the sponge; called collar cells. • Flagellum: flagella spins to create water currents to pull in water and food • Collar: “trap” plankton and other fine particles from the water

  9. Choanocyte Choanocyte

  10. Structural Skeleton • Consists of either one or all of the following: • Spicule: microscopic needle-like spikes that are made of Calcium carbonate (CaCO3) or silica (glass). • Spongin: a fibrous protein made of collagen

  11. Sponge Skeletons Silica Spicules Limestone Spicules SPONGIN

  12. Sponge Body Types • 3 Kinds- • Ascon • Sycon • Leucon

  13. Ascon • Simple tube perforated by pores • Open internal part of tube is called the spongocoel (coel = gut) • Are vase-like • Least common type of sponge • Single opening to the outside called the osculum

  14. Sycon • Sponge wall is folded into canals • Choanocytes line the radial canals to move water osculum

  15. Leucon • Have an extensively branched canal system. • Multiple canals lined with flagellated cells • Multiple ostia for water to exit • Increased surface area means more water can move through sponge

  16. Body Forms Summary

  17. Reproduction • Sexual Reproduction- sponges are monoecious (male and female in the same body) • Release sperm and eggs into the water from the Osculum • Cross-Fertilization takes place in the ocean • Fertilized eggs form larvae which swim off looking for a place to settle

  18. Reproduction Sponge Releasing Eggs & Sperm

  19. Reproduction Cont’ • Sponges can regenerate (regrow) lost body parts through mitotic cell division (asexual) • Sponges also reproduce asexually by (budding)

  20. Reproduction Cont’d • Asexual Reproduction- involves the formation of gemmules • gemmules: resistant capsules that sponges release to survive unfavorable conditions. • When conditions become favorable, the gemmules sprout into sponges. gemmule

  21. CLASSES • Phylum Porifera • 3 Classes • Class Calcarea • Class Hexactinellida • Class Demospongiae

  22. Class Calcarea • Spicules made of Calcium Carbonate • Can have all three body forms • Most primative • Ex. Grantia

  23. Class Hexactinellida • Deep sea sponges • Can have syncon or leucon body forms • Often fused into an intricate lattice • Glass sponges (silica)

  24. Class Demospongiae • Spicules made of silica, spongin, or both. • Most common (fresh (green) & salt) • All are Leuconoid • Ex: bath sponge

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