Anthopleura stellula

Anthopleura stellula
Scientific classification
Kingdom:	Animalia
Phylum:	Cnidaria
Class:	Anthozoa
Order:	Actiniaria
Family:	Actiniidae
Genus:	Anthopleura
Species:	A. stellula
Binomial name
	Anthopleura stellula; (Hemprich & Ehrenberg in Ehrenberg, 1834)[1]
Synonyms[1]
	Actinia stellula Hemprich & Ehrenberg in Ehrenberg, 1834; Anthopleura elatensis England, 1969; Bunodes stellula (Hemprich & Ehrenberg in Ehrenberg, 1834);

Anthopleura stellula is a species of sea anemone in the family Actiniidae. It is found in the Indian Ocean and the Red Sea,[1] and is unusual among sea anemones in that it can divide itself in two transversely.

Biology

Anthopleura stellula is unusual among sea anemones in that it can divide by transverse fission. This is not a common method of asexual reproduction among these sea anemones but tends to occur as a reaction to stress, such as when an anemone is experiencing a lowering of the salinity. The fission involves the animal forming a transverse constriction before dividing in two, the oral portion growing a new pedal disc and the basal portion growing a new oral disc and pharynx. There are a few other sea anemones such as Gonactinia prolifera that can divide in this way, and all are rather small, primitive sea anemones with simple internal structures. Internal reorganisation often starts before the fission process commences.[2][3] During the fission process, an indentation occurs halfway down the column, new tentacles begin to develop below the constriction, and the two portions separate.[3]

Research has shown that a decrease in salinity encourages fission while an increase prevents it happening. When A. stellula was placed in an aquarium with the gem anemone Aulactinia verrucosa and the salinity was reduced, the fission of A. stellula induced fission in A. verrucosa, even though that species never spontaneously undergoes fission in other circumstances. It is thought that A. stellula produces "fission substances" when the salinity falls, and that these can circulate in the water and affect other sea anemones.[4]

References

Fautin, Daphne (2015). "Anthopleura stellula (Hemprich & Ehrenberg in Ehrenberg, 1834)". WoRMS. World Register of Marine Species. Retrieved 17 June 2017.
Shick, J. Malcolm (2012). A Functional Biology of Sea Anemones. Springer Science & Business Media. pp. 252–253. ISBN 978-94-011-3080-6.
Goffredo, Stefano; Dubinsky, Zvy (2016). The Cnidaria, Past, Present and Future: The world of Medusa and her sisters. Springer International Publishing. p. 240. ISBN 978-3-319-31305-4.
Schmidt, H. (1970). "Anthopleura stellula (Actiniaria, Actiniidae) and its reproduction by transverse fission". Marine Biology. 5 (3): 245–255. doi:10.1007/BF00346912.

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[WoRMS-1] Fautin, Daphne (2015). "Anthopleura stellula (Hemprich & Ehrenberg in Ehrenberg, 1834)". WoRMS. World Register of Marine Species. Retrieved 17 June 2017.

[2] Shick, J. Malcolm (2012). A Functional Biology of Sea Anemones. Springer Science & Business Media. pp. 252–253. ISBN 978-94-011-3080-6.

[Goffredo-3] Goffredo, Stefano; Dubinsky, Zvy (2016). The Cnidaria, Past, Present and Future: The world of Medusa and her sisters. Springer International Publishing. p. 240. ISBN 978-3-319-31305-4.

[4] Schmidt, H. (1970). "Anthopleura stellula (Actiniaria, Actiniidae) and its reproduction by transverse fission". Marine Biology. 5 (3): 245–255. doi:10.1007/BF00346912.