When we talk about algae, we often think of the green carpet found on coastal beaches. But what is really happening with this little-known species? With the advancement of research techniques, classification is evolving, and the word "algae" is increasingly becoming a generic term.
TO UNDERSTAND, LET'S START WITH A LITTLE BIOLOGY!
All cells have two aspects in common: they are all limited by a membrane which encloses their cytoplasm (internal environment of the cell).
They are distributed among many kingdoms. The main ones that interest us here are:
- Plants
Plant cells can, from their environment (including vitamins, minerals, gases, light), produce all the substances necessary for their survival. 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 that allows them to survive variable climatic conditions (temperatures, humidity). They have a nucleus that contains their genetic information (DNA).
- Animals
Animal cells depend, in addition to the environment, on plant and even animal cells at the top of the food chain to obtain the energy necessary for life. They must be nourished in order to carry out their metabolism, growth, and division. They also have a nucleus containing their DNA but do not have a cell wall.
- Bacteria
Bacterial cells, on the other hand, do not contain a nucleus ; their DNA is free in the cytoplasm.
ALGAE, A FAMILY A LITTLE APART
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 therefore makes them plants , but some are classified as bacteria .
This is the case for spirulina , which is located at the border of the three major kingdoms. Indeed, just like a plant cell , it uses photosynthesis to ensure its survival, just like an animal cell , it is not protected by a robust wall and just like a bacterium , it does not contain a nucleus.
And this large family at the crossroads of reigns is divided into 11 groups including 4 main ones:
- Cyanobacteria, historically called blue-green algae.
They do not contain a nucleus and are responsible for the enrichment of our atmosphere with O 2 . They are considered to be the origin of all forms of life currently known on Earth. This group is formed by 2 species, Aphanizomenon flos-aquae , Spirulina platensis , maxima and major , in other words, AFA-Klamath and Spirulina .
- Red algae
They bring together between 4000 and 6000 species established in a marine environment.
Porphyra umbilicalis , better known as Nori seaweed, is part of this group.
- Green algae
They are mostly green in color but Dunaliella salina , particularly rich in b-carotene, is an exception with a pink color.
This group includes Chlorella vulgaris , or more simply Chlorella , and Haematococcus pluvialis , which provides us with precious astaxanthin , among other things.
- Brown algae
They are mainly found in the marine environment and are present in large quantities in cold regions of the globe.
In this group, we find among others Ascophyllum nodosum , Black Seaweed, Fucus vesiculosus often simply called Fucus and Laminaria digitata which is part of the Kelp family.
Depending on their color, marine algae are present at different levels on the seabed. From the surface, green algae are encountered, then brown algae, and finally red algae.
MICRO ALGAE, ALGAE?
It's simply a matter of size ... like between micrometers and meters!!!
Indeed, algae can be formed from a single cell ( Chlorella pyrenoidosa for example) or from a cluster of thousands of cells ( Laminaria digitata among others). Their size thus varies from a few micrometers to several tens of meters.
The terminology of algae is constantly evolving thanks to current research. The terms used today may no longer be used in a few years, but the quality of their benefits remains unchanged, and their nutritional richness makes them natural food supplements of choice, regardless of the sweet name scientists choose to give them.
