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Name derivation:

akashiwo (Japanese) = red tide.


Akashiwo G.Hansen & Moestrup 2000; currently there is only one species (Guiry and Guiry 2018).

Class Dinophyceae; Order Gymnodiniales

Separated from Gymnodinium on the basis of large subunit (LSU) rDNA (Daugbjerg et al. 2000).

Type species:  A. sanguine (Hirasaka) G. Hansedn & Moestrup comb. nov.

Probable synonyms G. splendens and G. nelsonii.


Dinoflagellates unarmored (no heavy cellulose wall plates), contain chloroplasts with peridinin the principal carotenoid accessory pigment.  Apical groove curves around apex in a clockwise direction (Ibid.)

Similar genera:



Akashiwo sanguine is photosynthetic and also preys on small cyanobacteria such as Synechococcus (Bockstahler and Coats 1993).


Marine plankton;  often forms ‘red tide’ blooms but no toxicity has been reported (Ibid.) even though it has been the dominant dinoflagellate in red tides that have killed large numbers of seabirds.  In blooms that form foam, the foam itself is speculated to cause bird kills.  The foams act as surfactants coating marine birds and fouling their feathers, leading to hypothermia and death (Jessup et al.

Forms subsurface layers when nitrogen is limited (Reid et al. 1978).


Bockstahler, K.R., & D.W. Coats  1993.  Grazing of the mixotrophic dinoflagellate Gymnodinium sanguineum on ciliate populations of Chesapeake Bay.  Marine Biology. 116(3):477–487.

Daugbjerg, N., G. Hansen, J. Larsen and O. Moestrup  2000.  Phylogeny of some of the major genera of dinoflagellates based on ultrastructure and partial LSU rDNA sequence data, including the erectiohn of three new genera of unarmoured dinoflagellates.  Phycologia 39(4):302-317.

Guiry, M.D. and G.M. Guiry  2018.  AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.  http://www.algaebase.org; searched on 08 February 2013.

Jessup, D.A., M.A, Miller, J.P. Ryan, H.M. Nevins, H.A. Kerkering, A. Mekebri, et al. 2009. Mass Stranding of Marine Birds Caused by a Surfactant-Producing Red Tide. PLoS ONE 4(2): e4550. https://doi.org/10.1371/journal.pone.0004550

Terry, Lynne October 22, 2009). "Foam from ocean algae bloom killing thousands of birds.  OregonLive.

Reid, F.M.H., e. Stewart, R.W. Eppley, & D. Goodman  1978.  Spatial distribution of phytoplankton species in chlorophyll maximum layers off Southern California.  Limnology and Oceanography. 23(2):219–226.