Mollusca
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Mollusca


Symmetry
Body Plan
Digestion
Transport within the Body
Bilateral
Coelomate (Foot, for movement, Visceral Mass, contains most organs, and Mantle, heavy fold of tissue to cover Visceral Mass)
  • Open (most; dorsal heart pumps hemolymph through arteries into sinuses to bath organs)
  • Closed (Cephalopoda)
  • The heart and vessels carry blood throughout the body into spaces called Hemocoel
  • Cephalopoda: a closed circulatory system with continuous vessels and several hearts
  • Gas Exchange
    Method of Waste Disposal
    Nervous System
    Reproduction
    Important Distinguishing Feature
  • Mostly by diffusion with outer environment
  • Gills help to negotiate gas exchange with water
  • Bivalve: Water flows into mantle cavity through incurrent siphon, and flows back out excurrently
  • Gastropoda: the mantle cavity serves almost like a lung
  • Mostly by diffusion with outer environment
  • Nephridia removes nitrogenous wastes from hemolymph
  • Consists of a nerve ring around the esophagus, which nerve chords extend from
  • Gastropoda: gangliated nervous system
  • Cephalopoda: well-developed nervous system with a complex brain
  • Most have separate sexes
  • Gastropoda: External fertilization, are also hermaphrodites
  • Cephalopoda: sexes always separate with internal fertilization
  • Pattern of Early Embryonic Development? Protostome
  • No true segmentation
  • The Radula, or a movable, tooth-bearing strap of chitin to serve as a tongue