Whilst researching the boundary layer around corals I came across this amazing photograph by Professor Roman Stocker. The photograph shows the micro flow around corals that is normally invisible. The coral’s surface is covered with thousands of tiny cilia (hair-like structure) that stir the water with their oscillations. The mico flow created helps to mix the boundary layer around the coral with their surroundings, which plays an important role in their physiology, but on a larger scale is also important to ocean health and biogeochemical cycles.
The photograph won the International Science and Engineering Visualization Challenge (2013) through the use of microsclae photography. The coral used was Pocillopora damicornis and the image was created by placing the coral in seawater containing tiny nutrient particles under the lens of a microscope. The slight movement of two coral polyps and the dynamic flow of particles in the surrounding water were captured on video over a 90-minute period.
A single image was then created by superimposing information from the beginning and end of the experimental video to show the coral’s movement and the paths of the particles’ flow. As Professor Stocker explains, “the red coral surface and gold particle tracks show the coral and fluid flow at the beginning of the experiment, while the purple and blue represent the coral and particles at the end of the period. The presence of the vortex at both points in time indicates that the water flow generated by the coral’s cilia is a consistently robust feature of the microenvironment. The proximity of the dots to one another indicates how quickly water flowed; particles further away from one another indicate faster movement.”
This image shows how much we still have to learn about the ocean and coral. To check out the other winners click here.