Soft corals aren't just for show, though even scientists frequently see them as little more than a decorative carpet.
They play a vital role in the coral reef ecosystem, says a new study of reefs in the South China Sea.
Soft corals have a plant-like structure, resembling bushes, trees, or stems. Like hard corals, they're made up of large colonies of polyps that look like a single organism. They're anatomically similar to hard corals, but with a few crucial differences like the absence of a calcium carbonate skeleton.
Instead, tiny structures called sclerites, which look like pins, help soft corals to stay upright. These pins help to protect the corals against predators, too.
The role of sclerites doesn't stop there, scientists found. Calcium carbonate can gradually cement sclerites together, forming structures that are very similar to stony corals, they discovered. Cemented sclerites can also form boulder-like structures. In either case, soft corals play a more crucial role in building reef habitat than scientists ever realized.
Previously, scientists believed soft corals simply disintegrated, their sclerites scattering to the sea floor. Rather, cemented sclerites help to form habitat for fish, algae, snails and other organisms that live in coral reefs. They also help to protect the shore from large waves.
Like hard corals, soft corals are at risk from ocean acidification, which dissolves calcareous structures.
Combined with their high level of biodiversity - the reef-building genus Sinularia has 170 species--the high risk level makes protection and further studies crucial, says Professor Yehuda Benayahu of Tel Aviv University's department of zoology.
The researchers want to better understand how quickly soft corals can form reefs, especially under stressful conditions like rising water acidity.
Study partners included Tel Aviv University, National Taiwan University, the National Museum of Natural Science of Taiwan, and Academia Sinica.
Top Image Credit: Blue Soft coral close-up underwater Indonesia Sulawesi © Frogkick