Imma Perfetto
Cosmos science journalist
Despite appearances, not all corals stay put. The mushroom coral, Cycloseris cyclolites, can pack up and “walk” to new habitats and new research has shown that it does so in pursuit of blue light.
A team of scientists used high-resolution time-lapse imaging to discover that C. cyclolites moves using a mechanism known as “pulsed inflation”, which resembles the movement seen in jellyfish.
The coral inflates and deflates its tissue in rhythmic bursts to drag and propel itself forward. Once the series of pulses is completed, each bout lasting 1–2 hours in total, it deflates back to its usual size.
This behaviour is also widely used by other free-living coral species to burrow, right themselves when turned upside down, and eject sediment when buried during storms.
High-resolution time-lapse demonstrating the detailed biomechanics of pulsed inflation mobility in C. cyclolites. The video shows the inflation of peripheral tissues and the twisting and contraction of lateral tissues, which collectively drive the coral’s forward movement in a manner similar to jellyfish swimming. Credit: Dr Brett Lewis
“Our findings suggest that pulsed inflation is not just a survival strategy but a critical mechanism for migration and navigation,” says Brett Lewis from Australia’s Queensland University of Technology, lead author of the new PLOS ONE study.
Experiments also showed that C. cyclolites is strongly attracted to sources of blue light, with 86.7% of corals moving towards it compared to just 20% for white light. They also moved further, crossing distances of up to 220mm towards a blue light source compared to 8mm towards white light.
“The ability of Cycloseris cyclolites to move towards specific light sources is a fascinating parallel to other marine species like jellyfish, which suggests they are more neurologically sophisticated than previously thought,” says Lewis.
Time-lapse video demonstrating the biomechanics of pulsed inflation mobility in C. cyclolites. The video integrates footage of the topside and underside views. This combined perspective highlights the coordinated inflation and contraction of coral tissues, driving active locomotion by shifting surface contact via pedal structures and generating forward movement through lateral tissue contractions. Credit: Dr Brett Lewis
This could help C. cyclolites navigate towards its preferred habitats in deeper waters (10–60m) by detecting subtle changes in light. Light with lower energy – colours such as reds, oranges, and yellows – are filtered out quickly in water, while blue and violet light, which are higher energy, travel deeper.
Lewis says that the new findings have important ecological implications.
“Understanding their movement strategies could help scientists predict how migratory corals might resist, survive or adapt to changes in environmental conditions such as sea surface changes caused by climate change, which can be reduced by the deeper waters these corals migrate to,” says Lewis.
“With these climate-driven factors increasing, the faster the migration, the higher the chance of survival.”
