Orbicella annularis is one of three species of Orbicella coral found in the Caribbean. This species of Orbicella grows into clusters of long thick columns with large domed shaped tops. The three species of Orbicella are O. faveolata, O. annularis, and O. franksi.
The corallites and polyps of O. annularis are small star shaped, and extend above the surface of the coral. When polyps are extended they are small, usually 5mm in size and look the same as other Orbicella species.
The difference between the three species is the shape of the colony and the surface texture of the coral. If you are learning to identify Orbicella first focus on learning to identify the corallites and polyps, then try identifying each species.
Boulder Star Coral
Orbicella annularis is commonly known as the Boulder Star Coral because of the individual pillars created by the colony which look like small boulders. If you look between the boulders the tissue and coral skeleton connects each pillar. However, if sediments build up between the pillar the tissue between each boulder can die.
Orbicella can grow into varying colony shapes depending on what depth you find the coral. Corals which are growing deeper will spread out wider to capture more light while colonies in shallower water could have more peaks or rounded space to avoid excess light on the coral.
Orbicella can be found in brown, cream, yellow, gray and green. Coral polyps can be the same color or contrasting color for the colony. If you aren’t looking for this coral it is easy to mistake as rock since parts of the colony could have died off.
We get it, there’s a lot to take in while you’re diving. Especially if you are diving for the first time or even the hundredth time. You are thinking about your buoyancy, checking your air and taking in all the creature underwater.
But once you train your eyes to look at the reef you will start to notice each colony of coral has it’s own shape, color and different neighbors. Photographing coral is especially rewarding as you have the opportunity to identify the corals after your dive.
The Coral Diaries series is a list of corals we have seen while diving around the world. We’ve created this series so that you can learn more about corals, and how to identify them on the reef. We encourage you to send us your coral pictures and leave a comment in the section below to learn more about the interesting species you’ve found while diving.