meaning "pore bearer" - PowerPoint PPT Presentation

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meaning pore bearer n.
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  1. Porifera meaning "pore bearer" Sponge Group 36: Jessica Penney, Tonika Levy, And Kristen Young

  2. Evolutionary History • Previously assigned to a separate subkingdom, Parazoa • Closest single-celled relatives are thought to be choanoflagellates • Does not form a monophyletic group • Fossil records of sponges have been found from about 580 million years ago • Archaeocyathids were a type of coralline sponge • ~5000 known species; ~150 freshwater species

  3. Basic Characteristics • Cellular-level organization • Body support (“skeleton”) provided by spicules • Filter feeders through pores • Either radially symmetrical or asymmetrical • Spicules and potential biotoxin for defence • Adults are sessile; larvae are motile • Reproduction: • Hermaphrodites • Sexual ; Asexual

  4. Structure • Body is divided into three layers: • The outermost layer comprised of pinacocytes • The middle layer, mesohyl • The innermost layer, choanocytes • Pinacocytes (Epidermal cells) • Choanocytes (Collar cells) • Mesohyl (Semi-fluid matrix) • Water flow AsconoidSynconoidLeuconoid

  5. Classification • Phylum Porifera • Class Calcarea • Class Demospongiae • Class Hexactinellida

  6. Class Calcarea • About 400 described species in this group • Exclusively marine; shallower, sheltered waters less than 1000m • Tropical regions associated with the coral reefs • Members of this group have large structural spicules • Skeletons made of calcite • Mainly dull, some colorful

  7. Class Demospongiae • Contain the largest number of species with 4750 species organized into 10 orders • Marine environment; intertidal to the abyssal zone; some species inhabit freshwater • Silicate spicules or spongin fibers or both within their soft tissues • Brightly colored

  8. Class Hexactinellida • Glass sponges • Depths between 200 and 1000m • Abundant in the Antartic • Upright stature • Skeleton made entirely of silica

  9. Sources • http://animaldiversity.ummz.umich.edu/site/accounts/information/Porifera.html • http://en.wikipedia.org/wiki/Sponge#Evolutionary_history • http://course1.winona.edu/mdelong/Invertebrate/Porifera.pdf • http://www.buzzle.com/articles/porifera-characteristics.html • http://palaeos.com/metazoa/porifera/porifera.htm