An old friend of Coastwise, John Hudson, took members through the life of algae from their appearance over 3Bn years ago to their many uses curently, including as an important foodstuff.
They cover a huge range of forms, from microscopically small mobile organisms to large anchored seaweeds such as kelp. The locomotive varieties use a range of techniques; Euglena uses waving fronds - flagellae - to move, inluenced by phototaxis, or light as a stimulus. Pinularia uses mucilage ejection as a from of rocket propulsion, while Clusterium somersaults about.
Reproduction is similarly varied. For example, fucus varieties produce sperm and eggs by a specialised form of cell division called meiosis, while volvox, a colonial alga, can reproduce both sexually and asexually.
John described how algae are often involved in symbiotic relationships. Lichens, so common on rock and trees are an associatio between algae and fungus. Cyanobacteria, a primitive form of algae, are found in polar bear fur, although no one really knows why !
The ability of algae to fix atmospheric nitrogen to a usable form in plant growth allows large-scale rice production - a huge food source for many parts of the world. In addition, there are many medicinal uses of algae, including antiseptics and respiritory remedies.
This fascinating overview of a major taxonomic kingdom - the prokaryotes and eukaryotes - concluded with the role of algae in the very early evolution of life, with the incorporation in protobacteria of both a nucleus with DNA, and a mitochondrium as the energy source.
A major evolutionary step then took this forward to include chloroblasts, capable of converting light energy to sugars, which allowed plant life to start "only" 8Bn years after the formation of Earth.
Now, a further 6Bn years on, look where we are......