Phylum Porifera

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Phylum Porifera
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Introduction

• Sessile animals lacking true tissues
• 10 000 species known
• Resembles a sac perforated with holes.
• (porifera pore bearers)

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Anatomy
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Specialized cells

• Collar cells
• Line the central cavity
• Flagellated, generate a water current
• Collars trap food, ingestion by phagocytosis

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Specialized cells

• Amoebocytes
• In mesohyl
• Take up food, digest it and distribute nutrients
• Some can form spicules (skeleton)
• Can also form gametes

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Specialized cells

• Porocyte
• Form pores into central cavity (ostia)
• Epithelial cells
• Line outer part of sponge

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Nutrition

• Water is drawn in through ostia into the central
  cavity and flows out through the ocsulum.
• The central cavity is lined with collar cells
  that generate a current and trap food particles
  (food plankton).
• Digestion is intracellular.

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Reproduction

• Sexual
• Most are hermaphrodites
• Sperm exits through osculum, into another
  sponges ostia.
• Sperm taken up by collar cells and delivered to
  egg.
• Larvae is released and 1-2 days later attaches
  and forms a new sponge.

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Reproduction

• Asexual
• Regeneration
• A broken piece of a sponge can attach and form a
  new sponge.
• Budding
• Smaller sponge grows on parent sponge and
  eventually breaks off, attaches and forms a new
  sponge.

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THE END!