Phylum Porifera Pore bearing Sponges Phylum Porifera Overview
Phylum Porifera (Pore bearing) Sponges
Phylum Porifera Overview • Most primitive of the multicellular animals – There is some debate if sponges are complex colonial protozoans and not metazoans • Sponges – Over 7, 000 species – 2% of all sponges are freshwater, none are terrestrial
Phylum Porifera Overview • Sponges occur in shallow water habitats and vary widely in size (up to 1 m high) and shape • All sponges are sessile filter feeders
General Characteristics Multicellular All aquatic- Mostly marine, some freshwater Mostly sessile Filter feeders Body contains pores, canals, and chambers for water passages • Asymetrical or Radial symmetry • No head, mouth gut cavity or organs • Asexual and sexual reproduction • • •
Porifera Anatomy
Pores • Ostia- incoming water • Oscula (osculum)- outgoing water
Types of Cells
Pinacocytes • Almost true tissue • Thin flat epithelial-type cells cover exterior and some interior surfaces
Choanocytes (collar cells) • Act as a pump to bring water into the sponge
Archaeocytes/ Amoebocytes • Ameboid cells that move about in the mesohyl • Functions – Phagocytize particles – Retrieve particles for digestion • Types – Sclerocytes- spicules – Collencytes-spongin – Lophocytes - collagen
Sponge support • Collagen is found between the inner canals and chambers – mesohyl • Collegen is stiffened by adding microscopic mineral accretions (spicules) or additional protein fibers (spongin) or both
Spicules • Skeleton structures made of calcium carbonate (Ca. CO 3) or silicon dioxide (Si. O 2) • Siliceous spicules • Calcareous spicules
Sponge Reproduction • Asexual reproduction – Bud formation • http: //www. youtube. com/watch? v=z. Vv 1 a. AJvgx 0 – Regeneration following fragmentation – Somatic embryogenesis • http: //www. youtube. com/watch? v=N 462 j. ZFr 13 k
Sponge Reproduction continued • Sexual reproduction • Monoecious- have both female and male sex cells in one individual (Hermaphrodites) – Sperm arises from the transformation of choanocytes – Oocytes (eggs) arise from either choanocytes or amoebocytes • Viviparous – After fertilization the zygote is retained in the adult and derives nourishment from the parent and released as a larva • Oviparous – Oocyte and sperm are released into the water in hopes they will meet up
Porifera larvae • Neighboring sponges are fertilized by sperm entering through the ostia – Ciliated mouth less larvae (parenchymella) is released
Types of Sponges
Asconoid: Flagellated Spongocoels • Simplest organization- Small and tube shaped • Water enters the spongocoel through dermal ostia
Syconoids: Flagellaged Canals Look like larger versions of asconoid sponges Tube body Singular osculum Body wall is more complex and thicker than asconoids • Contains radial canals with choanocytes which empty into the spongocoel • •
Leuconoids: Flagellated Chambers • • Most complex sponge type Large sponges Numerous oscula Clusters of flagellated chambers
Classes of Sponges • Phylum Porifera – Class Calcarea (Calcispongiae) – Class Hexactinellida (Hyalospongiae)- Glass sponges – Class Demospongiae
Calcarea (Calcispongiae) • 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
Hexactinellida (Hyalospongiae) • Glass sponges • Spicules are made of silica • Usually found in deep water on soft substrates in the tropics 200 -1, 000 m • Spicules are six pointed and have a lattice-like structure • Cup, vase or urn shape
Demospongiae (most sponges) • Have spicules made of silicon dioxide (Si. O 2) or spongin or a combination of both • Most sponges belong to this class (90%) • Mostly found on the continental shelf • Spongia spp. (Bath sponge)
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