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Phylum Porifera The Sponges. Classes of Porifera. Class Calcarea (e.g., Leucosolenia ) Class Hexactinellida (e.g., Euplectella ) Class Demospongiae (e.g., Spngilla ). General Characteristics. Most are marine; a few live in fresh water one family Spongillidae
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Classes of Porifera • Class Calcarea (e.g., Leucosolenia) • Class Hexactinellida (e.g., Euplectella) • Class Demospongiae (e.g., Spngilla)
General Characteristics • Most are marine; a few live in fresh water one family Spongillidae • Metazoan, with loosely aggregated cells, therefore no organs or true tissues. • Asymmetrical or radial symmetry • Body with pores (ostia and osculum), canals, and chambers through which a water current flows.
General Characteristics • Epidermis of flat pinacocytes; • Inner surfaces lined with flagellated collar cells (choanocytes)-create water currents • matrix called mesohyl contains amebocytes • and skeletal elements • Skeleton of calcareous or siliceous crystalline spicules and/or protein fibers (spongin)
General Characteristics • Digestion intracellular • Respiration and excretion by diffusion • Nervous system absent • All adults sessile and attached to substrate • Asexual reproduction by buds or gemmules • Sexual reproduction by eggs and sperm • Free-swimming ciliated amphiblastula larvae
Class Calcarea • also known as Calcispongiae • have spicules of calcium carbonate • all marine Leucosolenia
Class – HexactinellidaThe Glass Sponges • Glass sponges; • have siliceous spicules, • body often cylindrical or funnel shaped
Class - Demospongiae • have siliceous spicules, spongin, or both • one freshwater family • Spongillidae • Has gemmules during the winter
