A.  General characteristics of multicellular animals
       movement
       increased size/thickness
       cell layers/tissues
       body axis

B.  Characteristics of Cnidarians

C. General Classification

D. Need to know
    1. Mobility without muscle or skeletal tissue
          work against hydrostatic pressure
          contractile processes of epidermal (longitudinal) and gastrodermal (circular) cells

    2. Gas exchange
          diffusion limitations (Fick's law of diffusion)
          movement of water into GVC via flagellum and cilia on gastrodermis cells

     3. Orientation without body axis
          Statocysts with sensory cilia and statoliths

E. Zooxanthellae

Class Hydrozoa