Do seaweed have eyes? ????

Diatoms, unicellular microalgae, are distinguished by their ability to transform light into vital energy through photosynthesis. However, a recent study reveals that they don't just capture light: they use it to find their way in deep water. This mechanism is based on sensors sensory called phytochromes.

Phytochromes are encoded in the genome of diatoms and make it possible to detect variations in the light spectrum at different depths. This valuable information guides the microalgae into their vertical position, allowing them to adapt their activity biological, even in waters subject to constant eddies. This ability is not universal, however. Researchers from CNRS and Sorbonne University have discovered that only diatoms living beyond the Tropics of Cancer and Capricorn have these sensors. The marked seasons of these regions would force these algae to adjust their behavior in the face of changes in temperature. light.

Based on data from the Tara Oceans campaigns, scientists observed that phytochromes also allow diatoms to measure the passage of time. An essential function for coordinating their photosynthesis according to the seasons, thus optimizing their survival in extreme environments.

The discovery, published in Nature on December 18, 2024, underlines the importance of research both in the laboratory and in the open sea. These combined studies provide keys to understanding how these algae react to current climate upheavals.

This work has also shed light on other unsuspected capacities of diatoms, such as their ability to consume organic matter. This process could play a still unknown role in the regulation of marine ecosystems. Furthermore, diatoms have recently revealed their symbiosis with bacteria capable of fixing nitrogen. This interaction biological underlines their fundamental role in maintaining the chemical balances of the oceans.

Understanding these mechanisms has become important for anticipating the effects of global warming. These microalgae, although invisible to the naked eye, demonstrate an incredible capacity for adaptation which could inspire new approaches in ecology.