Algae, microalgae, cyanobacteria... Finding your way around

Algae, microalgae, cyanobacteria... Finding your way around

When we think of seaweed, we often think of the green carpet found on coastal beaches. But what is this little-known species really all about? With advances in research techniques, classification is evolving, and the word "algae" is increasingly becoming a generic term.


All cells have 2 aspects in common: they are all bounded by a membrane enclosing their cytoplasm (the cell's inner environment).

They are distributed among many kingdoms. The main ones that interest us here are :

  • Plants

Plant cells can use their environment (including vitamins, minerals, gas and light) to produce all the substances they need to survive. This ability comes from the chloroplast, a compartment specific to these cells and the site of photosynthesis. Plant cells are also protected by a robust cell wall, enabling them to survive variable climatic conditions (temperature, humidity). They have a nucleus containing their genetic information (DNA).

  • The animals

In addition to the environment, animal cells are dependent on plant and even animal cells at the top of the food chain for the energy they need to survive. They need to be fed in order to carry out their metabolism, growth and division. They also have a nucleus containing their DNA, but no cell wall.

  • Bacteria

Bacterial cells, on the other hand, do not contain a nucleus; their DNA is free in the cytoplasm.


Algae are organisms generally found in wetlands, characterized by the absence of leaves, flowers, seeds and roots. They all possess chlorophyll and generally use photosynthesis to live. This ability makes them plants, but some are classified as bacteria.

This is the case for spirulina at the frontier of the three great kingdoms. Like a plant cell, it uses photosynthesis to ensure its survival, like an animal cell, it is not protected by a robust cell wall, and like a bacterium, it does not contain a nucleus.

And this large family at the crossroads of reigns is divided into 11 groups, 4 of which are the main ones:

  • Cyanobacteria, historically known as blue-green algae.

They contain no nuclei and are responsible for enriching our atmosphere with O2. They are considered to be the origin of all life forms currently known on Earth. This group comprises 2 species:Aphanizomenon flos-aquae, Spirulina platensis, maxima and major, in other words,AFA-Klamath and Spirulina.

  • Red algae

There are between 4,000 and 6,000 species living in a marine environment.

Porphyra umbilicalis, better known as Nori seaweed, belongs to this group.

  • Green algae

They are mostly green in color, but Dunaliella salina, which is particularly rich in b-carotene, is a pink exception.

This group includes Chlorella vulgarisor simply Chlorella, and Haematococcus pluvialis, which supplies us with the precious astaxanthin, among other things.

  • Brown brown

They are mainly found in the marine environment and are present in large quantities in cold regions of the globe.

This group includes Ascophyllum nodosum, black seaweed, Fucus vesiculosus, often simply called Fucus, and Laminaria digitata, a member of the Kelp family.

Depending on their color, marine algae are found at different levels on the seabed. From the surface, we encounter green algae, then brown algae and finally red algae.

See also: Astaxanthin benefits


It's simply a matter of size... like between micrometers and meters!!!!

Algae can be made up of a single cell( e.g.Chlorella pyrenoidosa ) or a cluster of thousands of cells( e.g.Laminaria digitata ). Their size varies from a few micrometers to several tens of meters.

Seaweed terminology is constantly evolving, thanks to ongoing research. The terms used today may no longer be used in a few years' time, but the quality of their contribution remains unchanged, and their nutritional richness makes them the natural food supplements of choice, whatever sweet name scientists may wish to give them.

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