Blue ridge coral, Heliopora coerulea, is a unique species of coral in the wild and in the aquarium.Despite being extremely widespread and common on wild reefs, for some reason blue ridge coral is pretty rare in aquariums, even though it is a hardy and interesting coral.
Heliopora is an octocoral, related to all the soft coral we know and love, but it is distinct in being the “only” species to build a hard skeleton made of iron-infused aragonite. For being such an ancient line of corals, we’ve always had our doubts about the blue ridge coral comprising just a single species as there is a lot of variety of shape and growth forms that these corals exhibit in the wild.
The two main forms of Heliopora blue coral found in natural reefs range from colonies that have mostly flat-bladed growth (laminar), and colonies which have more branching overall shape (columnar). Now a new study has found that the laminar and columnar blue ridge growth forms are both genetically distinct, and have different spawning times throughout the year.
As aquarists we tend to explain away the differences in colony shape of stony corals due mostly to habitat and the specific physical environment in which the coral is found. However while diving on reefs that are rich with growth of blue ridge coral you can often see flat bladed and branching colonies growing right alongside each other.
The new study performed by R.D. Villanueva and published in the summer issue of Marine Biodiversity neatly delineates the two growth forms of Helipora. In this paper the author makes the case for cryptic speciation based on genetic differences and especially the different times that these corals spawn, but he doesn’t go so far as describing one of the new growth forms as a new species.
The study demonstrated a clear difference between the two most extreme growth forms of blue coral, but further investigation will likely reveal that there are many intermediate growth forms which may also represent distinct species. We hope that this line of research about the species richness of Heliopora is explored further as we particularly like blue coral as an animal, and we’d love to know more about the biodiversity of this unique, and for a long time, singular species of stony octocoral.