Thalassiosira spp.

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Taxonomic Group:Diatom
Trophic Status:Autotrophic
Size Range:14-61 μm wide (Cupp 1943); 2-186 μm wide (Tomas 1997); 7-186 μm wide (Horner 2002), depending upon species
Key Characteristics:Valves rounded or flat, with areolae or delicate radial rows of punctuations, but structure is often difficult to see; numerous small chloroplasts; united in flexible chains by organic threads extruded by strutted processes, or sometimes solitary; chains or cells embedded in mucilage
Confused With:Any of the simple pill-box type centric diatoms; broad rules of thumb are as follows: Thalassiosira spp. have circular pores that are undifferentiated in the central region, a flat or undulated valve face in girdle view, an edge that does not go out of focus when viewed in valve view, and marginal processes
Toxin:None known