New research has unravelled the mystery of how microscopic cilia coordinate to move and propel marine creatures through water. Cilia are tiny, hair-like protrusions found in many organisms, including humans and many aquatic animals. Almost all marine plankton have a life stage where they have cilia, which act like microscopic oars,  fundamental to the organism’s  ability to feed, move and disperse through water, avoid predators, and select suitable habitats. Proper coordination of cilia is essential for the normal physiology of many organisms, from single cells to humans. Yet despite decades of research, the mechanisms of cilia coordination remain disputed. Scientists have  particularly investigated  how coordinated waves of activity known as metachronal waves occur, which are fundamental to moving the organism effectively. These patterns travel through the array of beating cilia like a Mexican wave through a crowd. To address this question, a team at the University of Exeter studied the larvae of the marine rag worm Platynereis, selected for its spherical body shape with one single band of cilia, and a very simple nervous system. Their research, funded by the European Research Council (ERC) and Wellcome, and published in Science Advances, used whole-body high-speed imaging to examine the wave behaviour, and…