Pictorial chart of the nematocysts of Periphylla periphylla (Scyphozoa, Coronatae)

I. Sötje and H. Tiemann

Scyphozoans have complex marginal sense organs (rhopalia) that are responsible for photoreception, equilibrium reception and sensory responses to other stimuli such as touch, chemicals, pressure and temperature. The gravity sensor inside a rhopalium is the statocyst containing crystalline statoliths.

The statocyst crystals have a trigonal shape. The crystal faces are indexed as {3 0 2} (headfaces) and {1 0 0} (sidefaces).

The anorganic material of statoliths is calcium sulphate hemihydrate (bassanite). Elemental analyses performed with EDX-spectroscopy show mainly Ca, S and O.

References:

Tiemann H, Sötje I, Jarms G, Paulmann C, Epple M, Hasse, B (2002) Calcium sulphate hemihydrate in statoliths of deep-sea medusae. Journal of the Chemical Society, Dalton Transactions 1266-1268
Becker A, Sötje I, Paulmann C, Beckmann F, Donath T, Boese R, Prymak O, Tiemann H, Epple M (2005) Calcium sulphate hemihydrate is the inorganic mineral in statoliths of scyphozoan medusae (Cnidaria). Dalton Transactions 1445-1550
Prymak O, Tiemann H, Sötje I, Marxen J, Klocke A, Kahl-Nieke B, Beckmann F, Donath T, Epple M (2005) Application of synchrotron radiation-based computer microtomography (SRï¿½CT) to biominerals: embryonic snails, statoliths of medusae, and human teeth. J Bio Inorg Chem 10:688-695