Ctenophora

CTENOPHORA

Comb jellies

The phylum Ctenophora includes oval shaped, gelatinous planktonic animals with an opening at one end which acts as the mouth. Its transparent body is cover by multiple longitudinal rows of hair like cilia that beat continuously, passing rhythmic waves of movement down the bands to propel the animal, creating breathtaking, flickering iridescent colours.Planktonic, carnivorous, feeding on quite large shrimp-like prey.

Characteristics:

1. Symmetry biradial(radial + bilateral) on an oral-aboral axis. Three germ layers with much mesoglea in between. No segmentation.

2. Body usually with eight external rows of comb plates (ctenes). No nematocysts except in euchlora). Tentacles with adhesive colloblast cells.

3. Cellular epidermis and gastrodermis. Mesoglea containing amoebocytes and muscle cells. (Mesoglea may be considered cellular, making the animals triploblastic.)

4. Mouth with digestive system present. Digestive system includes a "pharynx" of infolded epidermis and a stomach that branches in to an intricate canal system.

5. Nervous system diffuse with a characteristic aboral sense organ (statocyst).

6.Monomorphic.

7. Hermaphroditic (both female and male sex organs). Reproductive cells formed from endoderm in digestive canals. Life cycle includes a distinct larval stage (cydippid). No asexual development.

8. pores ending the digestive canal.