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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Conklin, E.J., C.H. Bigger and R.N. Mariscal. – 1977. The formation and taxonomic status of the microbasic q-mastigophore nematocyst of sea anemones. Biol. Bull., 152: 159-168. doi:10.2307/1540556

Cutress, C.E. – 1955. An interpretation of the structure and distribution of cnidae in Anthozoa. Syst. Zool., 4: 120-137. doi:10.2307/2411864

England, K.W. – 1982. On certain Actiniaria of the Indian and Pacific Oceans. M. Ph. D. University of Reading, UK.

Hand, C. – 1961. Present state of nematocyst research: Types, structure and function. In: H.M. Lenhoff and W.F. Loomis (eds.), The Biology of Hydra, pp. 187-202. Univ. Miami Press, Coral Gables, Florida.

Iwanzoff, M. – 1896. Uber den Bau, die Wirkungsweise und die Entwicklung der Nesselkapseln der Coelenteraten. Bull. Soc. Nat. Moscow, N. S., 10: 95-161 and 323-354.

Kramer, A. and L. Francis. – 2004. Predation resistance and nematocyst scaling for Metridium senile and M. farcimen. Biol. Bull., 207: 130-140. doi:10.2307/1543587 PMid:15501854

Östman, C. – 1987. New techniques and old problems in hydrozoans systematic. In: J. Bouillon, F. Boero, F. Cigogna and P.F.S Cornelius (eds.), Modern trends in the Systematics, Ecology and Evolution of Hydroids and Hydromedusae, pp. 67-82. Clarendon Press, Oxford.

Östman, C. – 2000. A guideline to nematocyst nomenclature and classification, and some notes on the systematic value of nematocysts. Sci. Mar., 64(Sup. 1): 31-46.

Östman, C., W.R. Kem and S. Pirano. – 1991. Nematocysts of the Mediterranean hydroid Halocordyle disticha. Hydrobiologia, 216/217: 607-613. doi:10.1007/BF00026520

Östman, C., J. Roat Kultima, C. Roat and K. Rundblom. – 2010. Ac- ontia and mesentery nematocysts of the sea anemone Metridium senile (Linnaeus, 1761) (Cnidaria: Anthozoa). Sci. Mar., 74(3): 483-497. doi:10.3989/scimar.2010.74n3483

Schmidt, H. – 1969. Die Nesselkapseln die Aktinien und ihre differ- entialdiagnostische Bedeutung. Helogol. Wiss. Meeresunters.,19: 284-317. doi:10.1007/BF01625610

Weill, R. – 1934. Contribution à l’ étude des cnidaires et de leurs nématocystes. I, II. Trav. Stn. zool. Wimereux, 10-11: 1-701.

Westfall, J.A. and C. Hand. – 1962. Fine structure of nematocysts in a sea anemone. In: S.S. Breese, Jr. (ed.), Conf. Electron. Microsc. 5 (Philadelphia), M-13. Academic Press.

Yanagihara, A.A., J.M.Y. Kuroiwa, L.M. Oliver, J.J. Chung and D.D. Kunkel. – 2002. Ultrastructure of a novel eurytele nematocyst of Carybdea alata Reynaud (Cubozoa, Cnidaria). Cell Tissue Res., 308: 307-318. doi:10.1007/s00441-002-0545-8 PMid:12037587

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