Porifera

Porifera - Class Hexactinellida Cambrian-R - glass sponges,...

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Fossil Algal Megaflora Stromatolites & Oncolites – cyano-bacterial colonies, layered sediment (flat/columnar vs spherical “algal biscuits”)
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Fossil Algal Megaflora Calcareous Green Algae (Chlorophyta) – Ord-R modern Halimeda and Penicillus
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Fossil Algal Megaflora Fossil Receptaculites – Dasycladacean Green Algae?
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Fossil Algal Megaflora Coralline Red Algae (Rhodophyta) – Ord - R Solenopora – Ord – Jr
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Porifera Simplest metazoa – heterotrophic multicellular Limited differentiation of cells, no coelom All sessile suspension feeders Record Cambrian – R, generally poor fossilization Marine & fresh
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Sponge Biology Choanocyte – “collar” cells, make current Sclerocyte – make spicules Spongocyte – make spongin Archaeocyte – general purpose in mesohyl Ostum – incurrent Spongocoel – cavity Osculum – outcurrent Reproduction – asexual by budding, sexual by release of egg (from archaeocytes) and sperm (from choanocytes) into water Gemmules – armored archaeocytes
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Sponge Systematics
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Unformatted text preview: Class Hexactinellida Cambrian-R - glass sponges, spicules of silica. Today common in cold deep waters. Hydnoceras Euplectella Sponge Systematics Class Calcarea Cambrian-R - calcareous sponges. Today warm shallow waters. Heteroactines Sphinctozoans ex. Astraeospongia ex . Girtyocoelia Sponge Systematics Class Demospongea Cambrian-R framework primarily spongin, a few siliceous spicules (monaxons, tetraxons 60/120, demas) Astylospongia Sponge Systematics Class Sclerospongea Sil-R calcareous & siliceous spicules or none. May occupy cryptic habits. Stromatoporoids now included here. Psammobiotic sponges Sponges living in sediment. Facilitate cementation of carbonate sand to produce hardgrounds. Beginning point for modern reefs. Archaeocyathids Early Middle Cambrian, marine. Shallow current-washed water, high tolerance to turbidity. Passive filterer? Cambrian reef builders, symbiotic algae?...
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Porifera - Class Hexactinellida Cambrian-R - glass sponges,...

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