Scientia Marina, Vol 74, No 3 (2010)

Dart formation in nematocysts of the sea anemone Metridium senile (Linnaeus, 1761) (Cnidaria: Anthozoa)

Carina Östman
Animal Development and Genetics, Evolutionary Biology Centre (EBC), Uppsala University, Sweden

Jens Roat Kultima
Uppsala University, Sweden

Sau Yu Grace Wong
School of Animal and Microbial Sciences, University of Reading, United Kingdom


In examining large acontia b-mastigophore and p-amastigophore nematocysts of the sea anemone Metridium senile (Linnaeus, 1761) darts were observed by interference-contrast light microscopy (LM) and scanning electron microscopy (SEM). The darts consist of closely packed spines detached from the shafts, still in three helical rows. Their spines form a hollow cylinder with a sharp tip and indented base, its width similar to that of an undischarged shaft but varying in length. b-mastigophore darts were more common than those of p-mastigophores and many were longer.


nematocysts; cnidae; sea anemones; darts; SEM

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