See how unicellulars illuminate the oceans: scientists understand how this happens

Scientists have discovered how a single-celled organism of the species Pyrocystis lunula produces a flash of light. This happens when its cell wall is deformed by mechanical forces. Through systematic experiments, the researchers found that the flash brightness depends on both the depth of deformation and the speed with which it occurs. The study is published in the journal Physical Review Letters.

Every few years, the heyday of microscopic organisms called dinoflagellates transforms coasts around the world, endowing waves with eerie blue light. This year, the impressive heyday of these organisms was in southern California and has become a particularly striking example.

An international team led by the University of Cambridge has developed unique experimental tools based on micromanipulation and high-speed imaging. This enabled scientists to see the mechanisms of light production at the level of individual cells. Visualizations showed how a unicellular organism of the species Pyrocystis lunula produces a flash of light when its cell wall is deformed by mechanical forces. Through systematic experiments, they found that the flash brightness depends on both the depth of deformation and the speed with which it arises.

Known as the “viscoelastic” response, this behavior is found in many complex materials, such as liquids with suspended polymers. In the case of organisms such as Pyrocystis lunula, known as dinoflagellates, this mechanism is most likely associated with ion channels. They are special proteins distributed on the cell membrane. When the membrane is loaded, these channels open, allowing calcium to move between cells in the cell. This causes a biochemical cascade that produces light.

Pyrocystis lunula

Despite decades of scientific research, mainly in the field of biochemistry, the physical mechanism by which the fluid flow initiates the production of light remains unclear

Raymond Goldstein, professor of complex physical systems at the Department of Applied Mathematics, Schlumberger

Scientists’ results show the physical mechanism by which a fluid stream triggers the production of light. In addition, visualizations clearly demonstrate how “elegant” decision-making can be at the level of one cell, the researchers say.

Ocean bioluminescence is used to protect against attack and is involved in the mating process. In the case of dinoflagellates, they use light to scare away predators.