Rhopalium

The edge or sensory bodies of umbrella jellyfish (Scyphozoa) and box jellyfish (Cubozoa) that can be found on the edge of the umbrella or bell of these cnidarians are called Rhopalium (plural: Rhopalia rsp. Rhopalien ) . They have the shape of small tentacles or clubs lined with endoderm , which arise from the exumbrella (upper side of the umbrella of the medusa ) and are protected by a cover flap.

Rhopalia of the ear jellyfish

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Rhopalia the box jellyfish

Statocysts ( organs of equilibrium) and ocelles ("eyes") are formed as sensory cells on the endodermal cells of the tip of the club. Inside there are numerous crystals (in the Cubozoa from Bassanite ) that act as statoliths and transfer the pendulum movement of the clubs to the sensory cells.

literature

W. Westheide; R. Rieger: Special Zoology. Part 1: Protozoa and invertebrates . Gustav Fischer Verlag, Stuttgart / Jena / New York, 1996. ISBN 3-437-20515-3