Coral reefs are more than just stunning underwater landscapes; they are the bustling metropolises of the ocean, serving as essential shelter, breeding grounds, and food sources for a vast array of marine life. Their intricate, three-dimensional structures provide refuge from predators and harsh currents, creating nurseries for countless juvenile fish and invertebrates.
From the vibrant clownfish nestled within anemones to the large, predatory sharks hunting along the reef’s edge, coral ecosystems support an astonishing biodiversity. Understanding the crucial role these reefs play in housing marine life is fundamental, whether you’re a curious novice or a dedicated coral restoration enthusiast.
Learning to positively identify coral species and understanding their preferred niches is crucial. By recognizing the specific conditions each species thrives in – water clarity, depth, current strength, and substrate – you’ll be able to locate them more effectively during dives or surveys.
This knowledge becomes particularly powerful in coral restoration efforts, where selecting and propagating the proper, locally adapted species ensures successful reef recovery and long-term ecosystem health. Understanding these nuances allows us to become better stewards of these critical habitats.
Six Types of Branching Coral
One of the first steps to becoming a coral spotter is learning to recognize coral growth forms. An perhaps the most recognizable of them all is branching corals. But even within this recognizable group, there are many varieties of coral branches.In this article, we will show you how to spot six different branching coral types, including some small polyp and some large polyp corals.
Acropora
Before delving into other branching corals, it’s essential to highlight the dominant genus, Acropora. This genus boasts over 150 recognized species, making it a cornerstone of reef ecosystems worldwide. While generally characterized by branching growth forms, Acropora exhibits an extraordinary diversity of branch morphologies. These range from robust, antler-like structures in species like Acropora cervicornis, providing vital habitat for large fish, to delicate, intricate twig-like branches in species such as Acropora millepora, offering refuge to smaller, more specialized marine life.
Acropora species are particularly sensitive to environmental changes, making them key indicators of reef health. Their rapid growth rates, when conditions are favorable, contribute significantly to reef framework construction and complexity, fostering biodiversity. This rapid growth is a key factor in why Acropora is often a focus for coral restoration projects. By fragmenting healthy colonies and outplanting these fragments, restoration practitioners can accelerate reef recovery and enhance structural complexity. However, their susceptibility to stressors like thermal anomalies and disease makes them vulnerable to rapid decline.
The sheer variety of Acropora branching patterns—from table-like formations to dense, bushy colonies—creates a multitude of microhabitats, each supporting unique ecological niches. Given the complexity and ecological importance of Acropora, a dedicated series exploring its diverse forms and functions is warranted in the future. Here is our Acropora overview video.
Small Polyp Branching Coral
Isopora
Isopora is a robust branching coral found on reef tops. You have a problem spotting this widespread coral species Isopora forms think flattened blades that are upright, stretching to the surface. There are some Isopora colonies which grow in an encrusting form, but the most common is branching.
Isopora colonies are covered in smooth, rounded corallites, and the color can be pale brown to a creamy white or yellow. You will find this coral at the shallow reefs and the crest of reef slopes down to 20m. There is only one species, Isopora palifera.
Pocillopora
Pocillopora is abundant in the Indo-Pacific and can be found shallowest to the deepest parts of the reef. There are almost twenty species of Pocillopora but they all have the same characteristic bumpy branches.
Sometimes the branches are densely packed or wide and spread out. It depends on the species and the flow conditions where you find this coral. The common name is the Cauliflower coral because of the short lumpy branches.
Seriatopora
Seriatopora is a branching coral that has thin branches and forms small compact colonies. The branches can have rounded branch tips or pointed branch tips which are mostly brown, yellow and sometimes pink.
The best way to identify this coral is by looking at the placement of each polyp which are often our during the day giving this coral a fuzzy appearance. In Seriatopora coral all the polyps line up in a neat row, or series. If you spot the polyps in a row you’ve got yourself a seriatopora.
Large Polyp Branching Corals
Euphyllia
Euphyllia is a hard coral which has long flowing tentacles. The tentacles can end in little hammer-shaped polyps or tentacles with short knobby branches that look like frogspawn. Within these two tentacle types there are some which grow in a branching form.
It is easier to see the hard branches once the coral is closed up. These short branches are all connected at the bottom and as they grow up they split apart. The polyp lives inside the branch and closes up at night or when it is being threatened by fish or other corals which get to close.
Plerogyra
Plerogyra is the first coral divers are surprised to learn is a hard coral. The common name for this coral is the bubble coral because it make round pearl shaped bubbles just like fish eggs and that is what most divers think it is.
The bubble coral can make two types of bubbles. One is a smooth grape shaped bubble and the other is a pearl shaped bubbles. Both are the same species just different shaped bubbles. The branches of bubble coral can continue to grow as old calcium carbonate builds up to form large stalks. The only living part of the coral is the soft bubbles at the tip of the branch.
Caulastrea
Caulasatrea is a corals that makes short branches and trumpet-shaped corallites. Each corallite is between 1-2 cm in diameter with branches up to 2-6 cm in length, depending on species.
The coral tissue of this genus is slightly inflated at the top lip of the corallite making a trumpet or bell shape appearance. In the picture below you can see the tissue inflated around the skeleton with white skeletal ridges surrounding the polyps mouth.
Once the corallite reaches a mature size you will notice a rounded corallite starting to create a peanut or figure 8 shape, before splitting in two. This is a unique way that Caulastrea polyps divide and continue to propagate. Each polyp once mature will split apart in the center and slowly start to build it’s own corallite home.
If you wish to join one of our coral nursery tours so our guide can give you an overview of the corals you will find. The proceeds from the coral nursery tours go towards coral restoration and supporting the local communities that run it with the Ocean Gardener curriculum.
If you wish to go further and get hands-on with coral restoration, consider taking one of coral restoration courses.
Get out there and start coral spotting today!