Ostreopsis ovata

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Ostreopsis ovata
Ostreopsis cf. ovata

Ostreopsis cf. ovata

without rank: Dinoflagellates (Dinoflagellata)
without rank: Dinophyceae
Order : Peridinales
Family : Ostreopsidaceae
Genre : Ostreopsis
Type : Ostreopsis ovata
Scientific name
Ostreopsis ovata

Ostreopsis ovata is a unicellular, armored algae belonging to the dinoflagellate group . The species produces a toxin that is toxic to humans and can cause algal blooms.


The shells of Ostreopsis ovata , like all members of the genus Ostreopsis , are flattened on the belly and back. The two bowls do not have a significant difference in size. The cingulum has two distinct structures: a ventral plate with a ventral pore and an adjacent, curved plate. The cells are drop-shaped, oval and narrowed on the abdomen. Ostreopsis ovata is the slenderest species in the genus. The shell surface is smooth and has small, evenly distributed pores 0.07 micrometers in diameter. The dorsoventral diameter is 47 to 55 micrometers.

The cells are photosynthetically active and contain a number of gold-colored chloroplasts . The large and oval nucleus is located in the back of the cell. There is evidence that the species is mixotrophic : prey organisms are enclosed with the ventral pore.

The reproduction occurs asexually through cell division.

Distribution and habitat

Ostreopsis ovata is rarely observed, populations are mostly found in protected, coastal areas of the tropical Pacific , in the Caribbean and in the Tyrrhenian Sea .

The algae live benthic , sometimes occur in plankton (tycoplanktic), or grow epiphytic .


The poison produced by Ostreopsis ovata is not known in detail. The poison is ingested by humans through contaminated food, especially mussels, or through swallowed water or inhaled spray.

Ostreopsis ovata is native to the tropical Pacific . However, when the temperatures are favorable, it can shift its occurrence further north or south. The species has been known in the Mediterranean since 1989 , where it caused problems several times and in 2005 and 2006 for bathing bans. The alga may have entered the Mediterranean Sea through ballast water from international shipping.

supporting documents

  • Maria A. Faust, Rose A. Gulledge: Identifying Harmful Marine Dinoflagellates . Smithsonian Institution Contributions from the United States National Herbarium, Volume 42, 2002. (online)

Individual evidence

  1. Art entry on algaebase.org , accessed May 24, 2009.
  2. a b c d Article about Ostreopsis ovata at www.dieuniversitaet-online.at accessed on May 20, 2009
  3. Report on bathing ban after algae plague in the Mediterranean at www.scinexx.de, accessed on May 20, 2009
  4. Poisonous algae contaminate Genoa's beaches at www.spiegel.de, accessed on May 20, 2009

Web links