200 Year Old Mystery Solved: Why Do Corals Pulsate?

If you have ever been scuba diving and seen pulsating coral, you may have wondered why such a simple specimen would engage in such an intense activity. Marine biologists from the Hebrew University of Jerusalem and the Technion – Israel Institute of Technology have now begun to discover the biological processes that make the pulsating coral, or Heteroxenia coral, move the way they do.

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MA student Maya Kremien, along with Professor Amatzia Genin from the Hebrew University and Professor Uri Shavit of the Technion, conducted research on this interesting coral species, common to the Eilat environment, due to its unique movements. Pulsating movements are known in other marine species like jellyfish, which do so for reasons of predation and feeding.

Yet corals are not known to engage in predation, so Kremien observed the coral continuously to understand the environmental or chemical reasons behind its movements, and her and her team made some riveting discoveries.

[youtuber youtube=’http://www.youtube.com/watch?v=cIUVtA1_if0′]

Using an underwater measuring device called PIV (Particle Imaging Velocimetry) that measures the flow of water around the coral accurately with lasers by capturing images and data computation, Kremien and her team were able to observe the corals’ environment at the resolution of a particle.

A 200-year-old mystery solved

Their experiment revealed that one of the reasons for coral pulsation was to mix the water around them to get the nutrients they need, and then to sweep the used water away. These essential nutrients include carbon-dioxide in the daytime, oxygen at night and phosphate and nitrogen at all hours.

The team discovered yet another reason for the corals’ unique motion that did not have to do with simply cleaning its environment. With the same machine in a controlled lab environment, the team discovered that the coral engages in a pulsating motion to maintain its photosynthesis rates by sweeping away extra oxygen. The presence of photosynthetic algae in the coral tissue is what has allowed coral species to remain one of the most ancient species, and the pulsating movements in the Heteroxenia coral help perpetuate this corals’ long existence.

Therefore, the team reached the conclusion that the pulsating movement of the coral maintains an essential chemical balance and helps it “breathe” through photorespiration.

The results of the study solve the nearly 200-year-old question (beginning with the research of Jean-Baptiste Lamarck) of why the Heteroxenia coral pulsates, but also may have important applications to the fields of engineering and medicine in the future.

Photo by Derek Keats