Lab 03 - Cnidaria & Ctenophora

Miscellaneous cnidarians

Pleurobrachia, a ctenophore

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Cnidarian and Ctenophora are a phyla of animals with radial symmetry and two tissue layers, exclusively aquatic, mostly marine. Cnidarians include anemones, corals, sea jellies ("jellyfish"), and other less known groups, whereas ctenophores are the comb jellies.

Today students became familiar with the typical morphology of most of the cnidarian groups, and a little of the behavior of one of them. Only one representative of the Ctenophora was observed.

The following groups were studied

Cnidaria

• Hydrozoa
  
  • Hydroida
    
    • Hydra
      
    • Gonionemus
      
    • Pennaria
      
    • Obelia
      
    • Plumularia
  • Siphonophora
    
    • Physalia
      
    • Vellela
  • Scyphozoa
    
    • Aurelia
      
    • Cassiopea
• Anthozoa
  
  • Hexacorallia
    
    • Metridium
      
    • Acropora
      
    • Fungia
      
    • Meandrina
  • Octocorallia
    
    • Gorgonia
      
    • Renilla
      
    • Stylatula
      
    • Leptogorgia

Ctenophora

• Cydippida
  
  • Pleurobrachia

We had live individuals of the genus Hydra, which students observed under a dissecting scope.  Movement was analyzed as a response to disturbance and as response to having food available (the branchiopod crustacean, Daphnia, the water flea [incidentally the animal with the record number of genes!])

Hydra feeding on Daphnia

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