BIO 2135 Chapter Notes - Chapter DigiDiv: Sponge, Mesohyl, Calcareous Sponge
8 Feb 2017
School
Department
Course
Professor
Document Summary
Choanocytes : collar-shaped cells microvilli collar surrounds a central flagellum flagellum pulls water between the microvilli, particles get trapped here and are ingested by phagocytosis. The path water takes through its aquiferous system defines the asconoid, syconoid, and leuconoid forms of sponges. Organized cellularly they don"t have tissues. Out pinacoderm, inner choanoderm surround mesohyl, containing spicules and spongin (form skeletal structure) Gas exchange, nutrient transfer, nitrogenous waste elimination occurs through diffusion. Sclerocytes: can differentiate into a variety of cell types. Muscle cells that conduct signals, surround pores secrete the mineralized structures of the body walls. All cells are totipotent: can differentiate into other cell types. Calcareous spicules can"t form due to pressure at depths in the ocean. Use calcium carbonate to build their spicules. Three- and four-rayed spicules unique to calcarea. Cellular adhesion proteins similar to those found in other animals, but not sponges. Some use gemmules, a form of asexual reproduction.
