BIOL 2325 Chapter Notes - Chapter 6: Demosponge, Leaf, Spongin
Document Summary
Cells can attach to each other or to an extracellular matrix. Connect to basal lamina(sheet of ecm) via adherens junctions. Tight junctions-cells bind together to prevent leakage of extracellular fluid. Gap junctions- provide channels between cells to allow for communication. Spicules-skeleton made of calcium carbonate or silica and collagen. Oscula- large pour that serves as a water outlet. Choanocytes- peculiar flagellated collar cells whos flagella maintain a current of environmental water through the canals that they line. There are 3 types of canal systems: asconoid, syconoid, and leuconoid. Use water current to filter food and waste. Simple organization and are small and tube shaped. Water enters through small dermal pores into a large cavity called spongocoel. Spongocoel is lined with choanocytes that pull the water through the pores and expel it through one large osculum. All asconoids are in the class calcarea. Choanocytes are folded back and forth to make canals. The folds the line are called radial canals.
