Porifera and Placozoa 1

Porifera and Placozoa 9/1/2005

Phylum Porifera

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Echinodermata Uniramia Crustacea Vertebrata Chelicerata Nematoda Protochordata Priapulida Kinorhyncha Loricifera Hemichordata Annelida Mollusca Bryozoa Apicomplexa Actinopoda Brachiopoda Phoronida Ciliophora Platyhelminthes Euglenozoa Rotifera Rhizopoda Cnidaria Granuloreticulosa Porifera

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Poriferan diversity

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Poriferan diversity

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Poriferan diversity

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Poriferan diversity

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Poriferan characteristics

z 98% marine, 2% freshwater z Among the first of multicellular (Metazoan) animals z Individual cells subordinate to the “organism” z Differentiation of cell types for division of labor – Choanocytes (food collection, reproduction) – Pinacocytes (outer protection) – Porocytes (regulate water inflow, guard against intruders) – Amebocytes or Archeocytes (food digestion, storage, waste disposal, sundry other functions) – Sclerocytes (secrete spicules) – Spongocytes (secrete spongin) z Non-cellular matrix uniting organism: – Spongin protein – Spicules (Ca, Si)

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Things sponges do not have

z Tissues (nor organs, etc) z Regular symmetry z Extracellular digestion z Sense organs (or nervous system) z Mobility

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Sponge structure

Osculum

Spongocoel

Inhalant pore

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Cells organised into layers (not yet “tissues”)

Pinacoderm

Mesohyl (non-cellular)

Choanoderm

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Pinacocyte (form pinacoderm)

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Porocyte

Dermal ostia

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Choanocytes

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Sclerocytes

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Amebocytes

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Internal organisation

z 3 basic types – Asconoid – Syconoid – Leuconoid

Asconoid sponges

Osculum Spongocoel Water flow Ostium Porocyte

Syconoid sponge

Osculum Spongocoel Choanocyte

Leuconoid sponge

Osculum Excurrent canal

Choanocyte chamber

Feeding and Digestion

Choanocyte flagellum Microvillar collar Food vacuole Amebocyte in the mesohyl

Poriferan reproduction

Micropyle Asexual Asexual Spicule Budding Fragmentation Gemmule formation Sexual Many hermaphroditic