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

P. periphylla has the same two categories of nematocysts as other coronates (holotrichous isorhizas and heterotrichous microbasic euryteles), with a total of at least six different types. The capsules are very large in comparison to other scyphozoan medusae like Cyanea capillata, Cyanea lamarckii, Chrysaora hysoscella, Aurelia aurita and Rhizostoma octopus. One of the types (the giant eurytele) can reach a length from up to 100 �m. These euryteles are unique in becoming increasingly large with medusa growth, and in being the largest so far described from Scyphozoa. Lightmicroscopical pictures of the six types are shown in this pictural chart. For the examination tissue of fresh captured medusae were squeezed in glycerol on microscopic slides.

Reference used for the determination of Periphylla periphylla nematocyst-types:

• Werner B (1965) Die Nesselkapseln der Cnidaria. I. Klassifikation und Bedeutung für Systematik und Evolution. Helgol Wiss Meeresunters 12:1-39
• Jarms G, Tiemann H, Båmstedt U (2002) Development and biology of Periphylla periphylla (Scyphozoa: Coronatae) in a Norwegian fjord. Marine Biology 141(4): 647-657

© I.Sötje, 2006