"Gallery of Soft Matter" competition announces creative winners

The annual “Gallery of Soft Matter” competition recently announced its winners. The event featured various creative entries, including posters and videos that showcased interesting natural phenomena like wriggling worms and flowing solids. One standout video by Isabelle Eisenmann from the University of Amsterdam focused on a tiny green alga named Chlamydomonas reinhardtii. This single-celled organism moves through water using two flagella, similar to a little rowing boat. Although the algae need light to survive, too much light can be damaging. To handle this, each alga has a single eye that helps it sense light levels and swim towards darker areas. In experiments, researchers placed C. reinhardtii in a petri dish illuminated from all sides. With no available shade, the algae used each other’s shadows to find refuge from the light. This led to the algae forming unique patterns, like branches radiating outwards before pulling back into a central mass. By changing variables like population density and light intensity, the team created a model to predict how these patterns would develop. Eisenmann noted that the algae’s behavior is somewhat similar to that of emperor penguins, which cluster together to stay warm. However, the algae’s interactions are different. While penguins rely on nearby interactions, the algae’s patterns require influence over greater distances. This finding could be significant for studying other active matter systems in nature.