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Sponges Phylum Porifera
The most primitive multi-cellular animals that possess no proper organs Multicellular animals but do not contain true tissues Body is covered in pores and canals Sessile (permanently attached to a surface)
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Sponges All aquatic > 10,000 species: 150 freshwater species, 9,850 marine species Symmetry: Asymmetrical or radially symmetrical Classified according to shape (asconoid, syconoid, leuconoid)
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Asconoid Sponges Shaped like a simple tube perforated by pores
Spongocoel: open, internal part of tube Osculum: single opening to spongocoel
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Asconoid Sponges
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Asconoid Sponges
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Asconoid Sponges
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Sponge Anatomy
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Syconoid Sponges More complex than asconoid sponges Larger in size
Tubular shape with a single osculum Thicker body wall with longer pore canals Canals are lined by choanocytes
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Syconoid Sponges
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Syconoid Sponges
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Leuconoid Sponges Largest and most complex sponges
Made up of masses of tissue penetrated by numerous canals Canals lead to many small chambers lined with flagellated collar cells Central canal and spongocoel eliminated Thick body wall with many folds that allow for high surface area and low volume
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Leuconoid Sponges
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Leuconoid Sponges
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Leuconoid Sponges
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Leuconoid Sponges
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Sponge Anatomy Skeletons consist of spicules and spongin
Many sponges have a skeleton made up of spicules (spiny strengthening rods made of silica or calcium) Other sponges have a skeleton made up of spongin (a flexible, fibrous material) Some sponges have both
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Sponge Anatomy 3 layers: Epithelial: Outer protective layer
Mesenchyme: Middle jelly-like layer also contains skeletal sponging and spicules Inner: lined with choanocytes and forms the spongocoel
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Sponge Anatomy Types of Cells
Amoebocytes: mobile cells found in the mesenchyme Porocytes: cells that line the pores Choanocytes AKA collar cells Specialized cells with a jelly-like collar and a single flagellum Collar traps plankton Flagellum creates water current These cells line the central canal and pores
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Collar Cell Flagellum Collar Cell body
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Sponge Anatomy Types of Cells (cont.)
Pinacocyte: cells that form the epithelial layer
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How Do Sponges Eat? Large volumes of water pass through a sponge’s body every day (5.3 gallons for a large sponge) Filter plankton and detritus from water Particles of food are trapped by jelly-like collar of choanocyte and is phagocytised by cell body Wastes are excreted into spongocoel and expelled through osculum
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How Do Sponges “Breathe”?
All cells of a sponge are in continuous contact with water Water currents created by flagella of collar cells draw oxygenated water into the sponge and force oxygen-poor water out of the osculum Oxygen diffuses into all body cells
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Not Much of Anything Sponges don’t have
a nervous system a circulatory system muscles a digestive system Why? Because they don’t have any organs which are needed to make a “system”…they don’t even have tissues that make up organs!
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Sponge Reproduction Only way a sponge species can disperse and colonize new areas Both sexual and asexual reproduction Regeneration can also be a means of reproduction
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Sponge Reproduction Sexual
production and release of large numbers of sperm cells released in clouds sperm transported to other sponges by water currents flagellated amphiblastula larvae (free swimming larva)
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Sponge Reproduction Asexual Budding: Cuttings: (Regeneration)
parent sponge produces gemmules, each of which can develop into a new sponge bud develops and then breaks off parent, then attaches to the substrate Cuttings: (Regeneration) When cut or torn sponges can regenerate to repair itself If a section is removed entirely it can grow into another sponge
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Threats and Predators of Sponges
Sedimentation: clog up pores agricultural practices deforestation dredging or other disturbance of water Parasitism Aquatic and terrestrial-based pollutants kill or weaken sponges Reef destruction destroys sponge habitats
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Threats and Predators of Sponges
Predators of sponges include: fish sea slugs humans (for commercial use, not for food)
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