Heliopora coerulea, commonly called blue coral, is very common throughout Kwajalein Atoll and the rest of the Marshalls. It can form massive coralheads, especially in shallow water along interisland reefs where the water rushes across the reef at low tide. The long reef between Bigej and Meck Islands is an especially good place to see it in quantity. Although called blue coral, its color in life can be affected by the zooxanthellae in its soft tissue, often giving it a greenish brown color. The dead skeletons are blue.
Heliopora coerulea is apparently highly variable in growth forms, but some, like those in the two photos immediately below, have thin branches that resemble descriptions of the recently described Heliopora hiberniana. A broken branch to reveal blue or white color would determine the species.
With Millepora fire coral.
Interesting difference in the polyps in the two photos below.
Growing alongside some plating coral.
Specimens occasionally bear odd circular marks which may be dead spots. Vaguely similar but larger circular marks are sometimes seen on coralline algae, and these are caused by a bacterial infection. We do not know what causes the marks on Heliopora.
Created 27 October 2020