Everyone believed corals were immobile, but that's not true: there is something that can make them move.

The ocean covers a vast majority of the Earth's surface and is home to numerous species, including corals. While these creatures may appear to be stationary, that's not entirely true: different species are capable of moving not just their branches. In a new study, researchers examined how corals move and what drives their movement, as reported by IFLScience.

According to the study's author, Dr. Brett Lewis, not all corals are attached to a substrate — some are solitary and live freely in the ocean, enabling them to migrate in search of better conditions. However, the lifestyle of these mobile corals and how they move and navigate during migration has long remained a mystery to scientists.

In their research, scientists focused on the mushroom coral Cycloseris cyclolites. Members of this species are generally small, with the largest reaching about 9 centimeters. It is known that young corals typically start their journey attached to harder substrates, but as they mature, they descend into deeper waters.

The researchers proposed that free-living mushroom corals likely move due to wave action or by hitching rides on other animals. Another possibility is that they are capable of moving by inflating and deflating parts of their bodies. During the study, the scientists were also interested in how corals reacted to various light stimuli.

It is known that blue light wavelengths prevail in deeper ocean layers, so the scientists aimed to compare coral movement in response to blue and white light to determine their preferences. During the experiment, aquariums covered with darkened enclosures were created, allowing for precise assessment of the animals' reactions to a single light source.

Next, the team set up time-lapse cameras and recorded the directions in which the coral moved over a 24-hour period. It is worth noting that the overall experiment consisted of 16 separate trials:

• 6 with white light;
• 7 with blue light;
• 3 with both blue and white light.

The distance traveled by the coral was recorded by measuring the position of the coral's mouth at the beginning and end of the experiment. The results showed that 86.7% of corals moved towards the blue light, while only 13.3% moved towards the white light. Researchers also found that corals did not move continuously, but rather in bursts followed by periods of rest. During the experiment with the combined blue and white light, all corals moved towards the blue light and away from the white light.

The scientists observed that the tissues at the base of the corals inflated, creating lift. The animals also increased their surface area using their ventral foot and manipulated their tissues through contraction and twisting movements, allowing them to advance. The researchers noted that these movements resembled jumping. After jumping, the corals deflated to their normal size. The team also pointed out that an inflated coral passively moved with the water current, albeit not towards the light.

It is suggested that this new information may further assist scientists in the restoration of coral species that are currently suffering from rising global ocean temperatures.