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Galaxy coral forms the largest hard coral colonies in Gorontalo. Massive mounds and columns of this spiky coral astound passing divers.
Stars of the Reef
A colony of Galaxy coral is made up of countless individual corallites. A single Galaxy corallite measures between three and four millimeters. A corallite is composed of a circular polyp, which is living. Surrounding the polyp are ridges that radiate from its center. These radiating ridges serve to protect the polyp from predators. These radiating ridges give each individual polyp the appearance of a star. A colony composed of countless stars gives rise to a galaxy of coral.
However, divers should be careful when approaching Galaxy coral. Those radiating ridges are extremely sharp and can easily cut one’s skin. Moreover, the scientific term for radiating ridges is septa.
The most common Galaxy coral in Indo-Pacific waters is Galaxea astreata. Usually, its colonies are low and encrust the substrate. At other times, it forms upright columns. For Galaxea astreata, its septa count is eight to twelve. Usually, it does not fully extend its polyps during the day. This helps protect it from daytime predators. In the closeup shot from Gorontalo, note the white-tipped polyps in this daytime photo.
Galaxy coral in Gorontalo
The large and notable Galaxy colonies of Gorontalo are most likely Galaxea astreata. In total, there are ten species of Galaxy corals. Possibly, Galaxea fasicularis is the coral found at dive sites here because it forms the largest known colonies. In Gorontalo, Galaxy corals form colonies larger than a city bus. This colony size is far larger than any described in scientific literature. In the wide angle shot from Gorontalo, note that the corals far in the background are still part of this massive colony of Galaxy coral.
Two factors contribute to the giant size of Galaxy colonies in Gorontalo. The marine environment here is extremely healthy. Also, Galaxy corals possess special sweeper tentacles. These are a defensive organ tipped with powerful stings. Those stings keep other corals from living close by. That makes room for the colony to expand.
Galaxy corals not only feed on plankton caught with the polyp’s tentacles. Inside its body live zooxanthella. These convert sunlight into food. Notably, Gorontalo lies slightly north of the equator, so sunlight is abundant.
For your chance to marvel at the Galaxy coral found in Gorontalo, please book your dive trip with us.