Deep Sea Cold-Water Corals Fuse Their Skeletons to Build Reef Habitats

It turns out that cold-water corals may just get along with others in an unusual way. Scientists have found that the coral, Lophelia pertusa, can fuse skeletons of genetically distinct individuals.

These corals live in the cold, dark depths of the ocean, exposed to strong currents as they provide a stable base for deep ecosystems. In fact, these corals are considered excellent reef-builders. Now, scientists have uncovered why that is. It turns out that even genetically different individuals can fuse their skeletons to one another.

The scientists first spotted this phenomenon on an expedition with the German submersible JAGO and the research vessel POSEIDON. They spotted two reefs off of the coast of Norway with these features.

"Normally it is very hard to see where one coral ends and another begins," said Sebastian Hennige, one of the researchers, in a news release. "But on our dives with JAGO, we were able to find reefs where orange and white types of the coral fused together. Coming from a tropical coral research background, seeing coral fusing like this instantly grabbed my attention, so we were able to successfully sample some corals for genetic and skeletal tests to prove that fusion happens between different individuals."

Previously, scientists assumed that these massive reefs were made by siblings joining together. But it seems that isn't always the case. Instead, genetically distinct individuals also fuse with one another.

"This discovery highlights not only how much we have to learn about deep-sea ecosystems but how important advanced technologies are in deep-sea exploration," said Murray Roberts, one of the researchers. "The chance to explore these deep coral reefs with the submersible JAGO allowed us to observe the corals fusing and get the all-important samples back to the ship and into our labs."

The findings are published in the journal Scientific Reports.