About Phyllodiscus semoni Kwietniewski, 1897
Phyllodiscus semoni has a broad basal disc that attaches it to its substrate. The lower part of its column is smooth, while the middle section holds a radially arranged series of pseudo-tentacles. These are thick, stalked, branched outgrowths, and their appearance varies widely between individual organisms. Hemispherical vesicles sit on these branches, and occasionally on the stalks. These vesicles hold nematocysts that contain both short and long-shafted stinging threads. The upper section of the column is short and smooth, and bears only a small number of nematocysts. The oral disc has a marginal ring of up to 160 long tentacles, two feeding grooves called siphonoglyphs, and a central mouth.
