Home / Rhodophyceae / Cyanidiales / Cyanidium

Home button

Click on images for larger format

Name derivation:

Greek kýanos, blue (Ref. Gérard Giraud 2021 Wikipedia Cyanidium)



Cyanidium  Geitler  1933;  1 of 7 species descriptions is currently accepted taxonomically (Guiry and Guiry 2013).

Order Cyanidiales;  Family Cyanidiaceae

Although currently classified within Rhodophyceae (red algae), Cyanidium is blue. Unlike most red algae it does not produce the red pigment phycoerythrin, but does produce phycocyanin (blue pigment) along with chlorophyll a (MacColl and Guard-Friar 2018).




Spherical unicells 2 6 μm diameter containing one large cup-shaped chloroplast.


Similar genera:



Thermophile: Acidic hot spring pools, 57 C, pH 2 4. Cyanidium caldarium is able to grow in media supplied with 100% CO2 (Seckbach et al. 1970, 1971). Optimal growth of several strains of C. caldarium is ~ 40-45 C and at pH 0 - 4, while the aquatic habitat range is 20 - 65 C and pH 2-4, and the terrestrial habitat range is 12 - 57 C and pH 0 - 5 (Doemel and Brock 1971).

C. caldarium is photosynthetic and heterotrophic, so likely mixotrophic (Ibid.)



Doemel, W.N., and T.D. Brock 1971. The physiological ecology of Cyanidium caldarium. J. Gen. Microbiol. 67:17-32.

Guiry, M.D. and G.M. Guiry 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 28 February 2013.

MacColl, X. and D. Guard-Friar 1987. Phycobiliproteins. CRC Press.

Seckbach, J., P.M. Shurarman, and F.A. Baker 1970. Algae thrive under pure CO2. Nature 227:744-745.

Seckbach, J., H. Gross, and M.B. Nathan 1971. Growth and photosynthesis of Cyanidium caldarium cultured under pure CO2. Isr. J. Bot. 230:84-90.