ZOO 2700 Lecture Notes - Lecture 15: Hermaphrodite, Hemocyanin, Nephridium
28 Mar 2018
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Lecture 15: mollusca: dorsal mantle with secreted chitin cuticle and calcareous spicules, radula, foot and paired pedal retractor muscles, bipectinate gills, tetraneural nervous system, pair pedal nerve cords, pair of visceral nerve cords. Mantle (or pallium: elaborated portion of the body wall over visceral mass, mantle epithelium secretes the shell. Apomorphies: tetraneural nervous system, pair pedal nerve cords, pair of visceral nerve cords, dorsal mantle with secreted chitin cuticle and calcareous spicules, radula. Ctenida composed of leaf-like filaments extend from supporting axis. Filaments are ciliated: propel h2o across surface, sort out food particles, bring o2. Monopectinate: one sided; bipectinate: 2 rows of filaments. Countercurrent blood movement: h2o moves in opposite direction of blood, more efficient o2 extraction. Osphradium: sensory organ hanging in the inhalant water current, monitor water entering mantle cavity, high sediment content reduction of ciliary beating= protects gills. Pedal hemocoel: blood sinus (hydrostatic extension) Retractor muscles: pulls shell towards foot.
