By Isabelle Charmantier
However, this is not a snowflake. It is a photograph of the mass development of the flagellate protozoan Bicosoeca on Asterionella. Asterionella is a genus of pennate freshwater diatoms, which are frequently found in star-shaped colonies of individuals, and therefore look remarkably like snowflakes. Diatoms are a major group of algae, and when we think of algae, we often think of seaweeds, algal blooms, and the slimy, slippery plants that render walking in a stream in our bare feet treacherous.
And are algae plants anyway? There are some algal species that can act both as plants and as animals at the same time.
Algae can be quite beautiful, especially seen up close through a microscope. The Victorians certainly thought so and collected algae, pressed on herbarium sheets, and under slides. Victorian microscopists created artful arrangements of diatoms that were sold as miniature curiosities, beautiful patterns invisible to the naked eye that would come to life under a microscope. Today, Klaus Kemp is the only living practitioner of that singular art form, which displays nature in a structured and ordered way.
Key facts on algae:
- Algae are at the base of the food chain;
- They are found in marine and freshwaters, anywhere that has moisture;
- There are hundreds of thousands of species, new ones are continually being identified;
- They are many different groups, such as the Bacillariophyta (diatoms) and Cyanophyta (blue greens);
- Some forms are toxic but some are edible; some have commercial uses;
- They range in size from single cells to massive kelps.
References
Canter-Lund, H. and Lund J., Freshwater Algae. Their microscopic world explored, Bristol, 1995.
Webpage links and embedded video links:
You can see a short film about Klaus Kemp and his diatom arrangements here: https://vimeo.com/90160649
Many of Hilda Canter-Lund’s photographs are available on the Freshwater Biological Association’s digital archive: http://www.environmentdata.org/archive/fbaia:pshc_collection
More on algae: http://www.algaebase.org
Isabelle Charmantier is the Information Scientist at the Freshwater Biological Association @freshwaterbio
Editor’s note: while all these organisms fall within the traditional remit of botany only some are still considered to be green plants, the others fall into the Stramenopiles (Heterokonts) and are a lineage closely related to green plants.