Porifera
 Simplest metazoan
 Cell level of organization
– Few cell types
– No true tissues
 Feed on material suspended in water
 Motile as larva - sessile as adult
Pores
 Ostia
– Small pores
– Water inlets
– Multiple ostia lead to canal system
 Osculum
– Large pores
– Water outlets
– Certain forms have more than one
Canal Structure
Canal Structure Summary
 Asconoid
– Simple canals, low surface area
– Flagellated spongocoel
– Large osculum
 Syconoid
– Convoluted canals, high surface area
– Flagellated canals
– Large oculum
 Leuconoid
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–
–
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Meshwork of canals, high surface area
Flagellated chambers
Small osculum – often more than one
Most efficient movement of water
Cross Section
Four Types of Sponge Cells
Cell Types
 Pinacocytes
– External epithelia
 Porocytes
– Form the walls of the ostia (pores)
 Choanocytes
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–
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Flagellated cells with microvilli collar
Trap food particles
Line the spongocoel, canals or chambers
Similar to ancestral Choanoflagellates
 Archoeocytes
– Ameboid in structure
– Differentiate into specialize cells
• Sclerocytes – spicules
• Collencytes – collagen
Food Trapping
Sponge Skeleton
 Spicules
– Siliceous – silicon based
– Calcareous – calcium carbonate
 Spongin
– Fibrous collagen
 Sponges can have skeletons based on either
spicules, spongin or both
Spicules
Sponge Development
 Sponges produce both oocytes and sperm
 Parenchymula – product of sexual reproduction
– Swims freely
– Flagellated cells on outside migrate inward while developing
Gemmule Structure
 Asexual reproduction
 Archaeocytes – able to differentiate into any cell type
 Resistant to harsh conditions
Hexactinellida – Glass Sponge
Demospongiae
Leuconoid Forms
Demospongiae
Leuconoid Forms