Topic #1: Defining Characteristics

• Medusa is the dominant form in contrast to Hydra whose dominant form is polyp
• Mesoglea is thicker and made up of cell
• Its bell margin lacks Velum which is why it is called Acraspedote
• Craspedote = having velum

  Acraspedote = having no velum
• Its guts are septate and divided into radial canals
• Its gonads are gastrodermal
• It has Rhopalia which bears the sensory organs Ocelli and Statocyst
• Ocelli

  • photo receptor
• Statocyst

  • for balance
• Scyphistoma undergoes strobiliation to produce young Medusae
• Schypistoma

  • term for the polyp stage of Scyphozoa
• Ephyra

  • young medusa
• Strobilation

  • asexual reproduction by transverse division of the body into segments