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SURVEY OF THE ANIMAL KINGDOM. PHYLUM PORIFERA. OVERVIEW Most primitive of the metazoans Over 7,000 species, approximately 40 species that occur in local waters 2% of all sponges are freshwater, none are terrestrial - PowerPoint PPT Presentation
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SURVEY OF THE ANIMAL KINGDOM
PHYLUM PORIFERA
• OVERVIEW– Most primitive of the metazoans– Over 7,000 species, approximately 40 species that
occur in local waters– 2% of all sponges are freshwater, none are
terrestrial– Sponges occur in shallow water habitats and vary
widely in size (up to 1 meter high) and shape– All sponges are sessile filter feeders
PHYLUM PORIFERA
• CHARACTERISTICS– Cellular level of organization, without true tissues– Adults exhibit radial symmetry or are
asymmetrical– Possess totipotent cells– Possess unique flagellated cells (choanocytes)
that create water flow through a water current system
PHYLUM PORIFERA
• CHARACTERISTICS– Outer and inner cell layers lack a basement
membrane– Outer and inner cell layers divided by a noncellular
layer (mesohyl) that contains some cells and skeletal material --- collagen
– Body support (“skeleton”) provided by spicules composed of calcium carbonate (CaCO3)or silicon dioxide (SiO2)
PHYLUM PORIFERA
• AMOEBOCYTES– Located in the mesohyl, with different roles• Phagocytic – role in digestion• Archeocytes – totipotent• Sclerocytes – spicule production• Spongocytes – secrete spongin• Collenocytes – collagen of mesohyl
PHYLUM PORIFERA
• REPRODUCTION– Asexual budding– Regeneration from broken pieces– Sexual• Hermaphroditic (some dioecious)• Eggs --- archeocytes or choanocytes• Sperm --- choanocytes• Neighboring sponges are fertilized by sperm entering
through the ostia
PHYLUM PORIFERA
• CLASSIFICATION– Class Calcarea– Class Demospongiae– Class Hexactinellida
PHYLUM PORIFERA
• CLASS CALCAREA– Have spicules made of
calcium carbonate– Mostly small in size (<15
cm), and form irregular masses
– NEVER contain spongin, restricted to shallow water, and strictly marine
PHYLUM PORIFERA
• CLASS DEMOSPONGIAE– Have spicules made of
silicon dioxide or spongin or combination of both
– Most sponges belong to this class (90%)
– Mostly found on the continental shelf
– Spongia spp. (bath sponge)
PHYLUM PORIFERA
• CLASS HEXACTINELLIDA– Spicules are made of silica– Usually found in deep water on soft substrates in the
tropics 200-1,000 meters– Spicules are six pointed and have a lattice-like structure– Cup, vase or urn shape– Euplectella spp. (deep sea glass sponge)