The Great Barrier Reef is made up of hard table coral.
Acropora, literally a porous branch or stem, is a type of coral commonly known as staghorn or table coral. Unlike other species of staghorn coral that branch similar to a tree or antlers, table coral branches horizontally like a flattened bush, which also resembles a table top. Thanks to the support provided by a coral bar connected to the seafloor, the coral table creates a shaded refuge for countless species of fish.
The Great Barrier Reef is located in the northeast of Australia.
Generally, coral is divided into two categories, soft coral and hard coral. Soft corals called “non-reef builders” are made up of soft “finger-shaped” extensions. Table coral is a hard coral, also known as a “reef builder”, that produces calcium carbonate skeletons that become the infrastructure of all coral reefs. Depending on the environment, coral can grow in many different ways. Some species of coral are round or flattened, some resemble a bush or plant, while many have extensions that branch out like trees.
The outer composition of the coral consists of coral polyps. Polyps are small invertebrates that cover the entire surface of the coral, responsible for providing nutrients to the body. Some species of coral contain polyps with the ability to capture small fish using tentacles covered in stinging cells.
Within the tissue of the coral lives a type of algae. This algae is responsible for the wide variety of colors associated with coral. Algae can also provide nutrients to corals. For stony corals, the main food sources are zooplankton and photosynthetic algae called zooxanthellae.
The distinctive shape of the table coral is key to its survival. This coral depends on zooxanthellae algae as its main food source. As the algae provide food through the process of photosynthesis, the table coral’s horizontal surface allows for maximum exposure to sunlight, resulting in an abundance of nutrients.
Like other coral species, table coral thrives in warm, shallow water as part of a coral reef community. A famous example is the Great Barrier Reef in Australia: due to its large amount of coral, it can be considered the largest living organism on the planet. Hundreds of species of coral, including table coral, play an important role in building the reef and the surrounding ecosystem. Around the world, reefs are in danger and are dying at an alarming rate due to the effects of global warming and pollution.