Diatoms

Life in glass houses

Champions of photosynthesis, these unicellular organisms appeared at the time of dinosaurs. They produce a quarter of the oxygen we breathe.

In this episode

  • dinoflagelle
    DinoflagellatePyrocystis elegans
  • diatomee
    Centric diatom
  • acanthaire_lithoptera
    AcantharianLithoptera mulleri
  • radiolaires
    RadiolarianAulacantha scolymantha
  • colozum
    RadiolarianCollozum inerme

Narration

Diatoms capture solar energy and produce a quarter of our planet’s oxygen. Despite their tough, siliceous shells, these phytoplankton are abundantfood for copepods and are at the base of the marine food chain.

Diatoms are single-celled organisms with nuclei and chloroplasts. They are protists living individually or forming chains, zig zags or spirals. The first diatoms – the centrics – appeared in the Jurassic age some 200 million years ago, as combinations of yeast-like organisms and algae. Over the eons,diatoms acquired new genes, shapes and complex metabolisms. They’ve becomechampions of photosynthesis, while retaining many properties of animal cells.

With other photosynthetic protists, they produce oxygen and absorb CO2. Over millions of years, diatom shells have sunk to the seabed, forming thick layers of silica and fossil fuels.
65 million years ago, diatoms survived the mass extinction of dinosaurs. They adapted to polar regions, where they still proliferate. Pennate diatoms appeared later and colonized new ecological niches. Some can glide over surfaces and congregate into a very thin layer called a biofilm. Pennates produce special metabolites and toxins that can ravage aquafarms.

When the sun shines, if iron and silica abound, diatoms flourish by dividing into smaller and smaller units. Survival demands that size be restored. Miniature diatoms transform into male and female gametes that join together and give birth to children much bigger than their parents.

Proliferation of diatoms at the poles result into explosive blooms visible from outerspace.

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Production
CNRS

Original Idea
Christian Sardet

Director
Sharif Mirshak

Scientific consultant
Chris Bowler

Texts
Christian Sardet

Images
Sharif Mirshak, Noé Sardet, Christian Sardet

Editing
Sharif Mirshak

Sound mix
Romain Strugala

Voice
Gregory Gallagher

Sound Engineer
Romain Strugala

Creative Commons Licence :
Attribution Non-Commercial
No Derivative

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