Hello all! I’m back again with more riveting information on your favorite algae, Zooxanthellae. I was excited to get more information on this little alga, however, when I began to scour the internet, there was not a whole lot popping up in my search engine.
It turns out that Zooxanthellae is an overarching term for an alga who lives in symbiosis with another creature, i.e. coral, jellyfish, sea worms, etc. (LaJeunesse, Todd, Parkinson, J., and Trench, R., 2012).
http://en.citizendium.org/wiki/Symbiodinium_microadriaticum
The actual scientific name for these guys is Symbiodinium. They are unicellular, photosynthetic dinoflagellates. Dinoflagellates are dimorphic, presenting as either a mastigote, which is basically the mobile version, or a coccoid cell, which is the stationary version. Symbiodinium starts its life as a smaller motile mastigote with two flagella that help it swim. Once the cell finds a resting place, it alternates with the coccoid phase. Cocci Symbiodinium cells can be between 6 and 13 micrometers in diameter depending on the species (LaJeunesse, Todd, Parkinson, J., and Trench, R., 2012).
https://oceanservice.noaa.gov/education/kits/corals/media/supp_coral02a.html
http://tolweb.org/Symbiodinium/126705
I tried to pin down just how many species of Symbiodinium there are and fell down a rabbit hole of phylogenetic trees, clades, and genetic biomarkers (Veron J.E.N., Stafford-Smith M.G., Turak E. and DeVantier L.M., 2016). The World Register of Marine Species, or WoRMS, recognizes 24 species but I have almost no way of knowing what species I saw while at the Georgia Aquarium (WoRMS Editorial Board, 2019).
It seems that the most common species of Symbiodinium is the S. microadriaticum so this will be the species I will be researching from here on out for simplicity sake. This species has a genome length of 808,226,712 base pairs encoding for around 49,00 genes (Aranda, M., et al . (2016). The cell walls of these dinoflagellates are made of cellulose and is only present when the cell is in the stationary phase. The plasma membrane stays intact in both life phases. Since these organisms are photosynthetic they contain chloroplasts or rather one single chloroplast in Symbiodinium’s case (LaJeunesse, Todd, Parkinson, J., and Trench, R., 2012).
Thats all the fascinating information I have on my microbe this week!
Until next time,
-L
Aranda, M., Li, Y., Liew, Y. J., Baumgarten, S., Simakov, O., Wilson, M. C., . . . Voolstra, C. R. (2016, December 22). Genomes of coral dinoflagellate symbionts highlight evolutionary adaptations conducive to a symbiotic lifestyle. Retrieved April 10, 2019, from https://www.nature.com/articles/srep39734
LaJeunesse, Todd, Parkinson, J. E., & Trench, R. K. (2012, July 4). Page: Tree of Life Symbiodinium. Retrieved April 10, 2019, from http://tolweb.org/Symbiodinium/126705
Veron J.E.N., Stafford-Smith M.G., Turak E. and DeVantier L.M. (2016). Corals of the World. Accessed 10 Apr 2019, version 0.01. http://www.coralsoftheworld.org/page/algal-symbiosis/?version=0.01
WoRMS Editorial Board (2019). World Register of Marine Species. Available from http://www.marinespecies.org at VLIZ. Accessed 2019-04-11. doi:10.14284/170