Porifera

• Phylum Porifera from Latin porus ‘pore’ + - fer ‘bearing’
• Mostly marine; All aquatic.

  • Radial or asymmetrical body

  • Multicellular; Body an aggregation of several types of cells.

  • Skeleton composed of calcareous or siliceous spicules and/or the collagenous protein, spongin.

  • Epithelial tissues present; no organs
• Phylum Porifera

  The animal phylum whose members are sessile filter feeders and either asymmetrical or radially symmetrical; body organized around a system of water canals and chambers; skeletal elements may be (spicules) composed of calcium carbonate or silicon dioxide (silica); spongin present in some; tissue-grade organization. Approximately 9,000 species.
• Class Calcarea

  Spicules composed of calcium carbonate; spicules are needle shaped or have three or four rays; ascon, leucon, or sycon body forms; all marine. Calcareous sponges. Grantia (=Scypha), Leucosolenia.
• Class Hexactinellida

  Spicules composed of silica and six rayed; spicules often fused into an intricate lattice; cup or vase shaped; syncytial epithelia; sycon or leucon body form; often found at 450 to 900 m depths in tropical West Indies and eastern Pacific. Glass sponges. Euplectella (Venus flower-basket).
• Class Demospongiae

  Brilliantly colored sponges with needle-shaped or four-rayed siliceous spicules or spongin or both; leucon body form; up to 1 m in height and diameter. Includes one family of freshwater sponges, Spongillidae, and the bath sponges. Cliona, Spongilla.
• Class Homoscleromorpha

  Anatomically simple and encrusting in form. Siliceous spicules small and simple in shape or absent. Occur at depths ranging from shallow marine shelves to depths of 1,000 m. Oscarella, Plakina.
• Phylum Porifera

  • Body with pores (ostia), canals, and chambers that form a unique system of water currents.

  • Sponge larvae are flagellated and motile, while adults are sessile
• Mesenchyme Cells - Located in the mesohyl layer (jelly-like layer
• Mesenchyme Cells - Located in the mesohyl layer (jelly-like layer)

  
  

  Amoebocytes - motile, "stem cells“ vital role in structure, digestion, reproduction, and regeneration.

  Sclerocytes - secrete calcareous or spicules.
• Mesenchyme Cells

  • Choanocytes – are cells with a flagellum surrounded by a collar of microvilli that traps food particles.

  • Pinacocytes – thin flat cells that line the outer surface of sponge. Some pinacocytes are specialized into tubelike, contractile

  • Porocytes – regulates water circulation.
• Sponge Body Forms

  • Ascon – the simplest of the three sponge body forms. Ascon sponges are vaselike, with choanocytes directly lining the spongocoel.

  • Sycon – a sponge body form appears folded characterized by choanocytes lining radial canals.

  • Leucon – the sponge body form that has an extensively branched canal system. The canals lead to chambers lined by choanocytes.
• Digestion - Food particles are trapped in mucus produced by the microvilli collar of the choanocytes and are ingested by phagocytosis.

  • Circulation - Their flagella beat to create the active pumping of water through the sponge.

  • Reproduction - Monoecious (both sexes occur in the same individual) but do not usually self-fertilize because individual sponges produce eggs and sperm at different times
• Clathrina clathrus (yellow-laced sponge) class calcarea