The Southern Great Barrier Reef is comprised of coral cays – underwater hills that were once completely submerged, until baby corals began to colonize the substrate, growing up and out towards the surface and sunlight. Corals form the most intricately stunning structures. They are the basis of all life on the reef.

Whether you’re planning your first ever trip to the Great Barrier Reef, or you’re lucky enough to be a regular visitor, here is some nerdy vocabulary every reef visitor – scientifically inclined or otherwise - should know! Try whipping these beauties out at your next gathering and impress all your friends with the animated stories and fun facts you bring home from the reef.

Polyp

A coral polyp is an animal closely related to a jellyfish. It extends its tentacles to feed at night, hoping to catch microscopic snippets of plankton floating through the water column. Take a closer look at corals and you may notice what appears to be an upside down jellyfish – or coral polyp – within the calcium carbonate cup it has created for itself.

Scleractinian

Describes the stony or hard corals that make up the majority of corals on the southern Great Barrier Reef. Scleractinian corals extract minerals from the ocean water to build a calcium carbonate skeleton, which provides the coral animal with protection from predators and forms the basis of the reef structure.  Hard corals dominate the Southern Great Barrier Reef and support an array of marine life, from the tiny coral polyps all the way up the food chain: without them, we wouldn’t get to experience turtles, manta rays, sharks and the myriad of colourful fish they attract!

Zooxanthallae (zoo-zan-thell-aye): Big name, big job!

Although you may not think it, plants are major building blocks of coral reefs! Zooxanthallae are itty bitty plant-like algae which find a safe home within living coral tissue. In return for a safe home, zooxanthallae photosynthesise, harnessing energy from the suns rays which is turned into sugars to feed the coral polyp. This gives the polyp enough energy to survive, grow, and build the hard reef structures we love to admire. Some corals depend on zooxanthallae for up to 90% of their food requirements. It’s a WIN-WIN relationship (and what marine biologists call a “symbiosis” – Latin for “living together)!

Fun Facts

The “Night Owls” of the underwater world

Most coral polyps are nocturnal, so they are hard to see with a naked eye in the middle of the day. If you look closely, you may see the calcium carbonate cups they create. Most corals will appear to have a browny-green to yellowy-orange earthy tone during the daytime. This is the zooxanthallae’s colour soaking up the sunlight!

Living Ancient History

If you are lucky enough to encounter structures larger than you are, there’s a good chance those corals have been around since well before your grandparents were born. Massive boulder corals are alive with hundreds of thousands of tiny polyps. They grow at a rate of around half a centimetre per year and some of them can reach 15m across. We’ll let you do the calculation to figure out just how ancient these structures can be!

Baby corals are the cutest!

Cyclones, disease and bleaching can impact a reef, leaving little more than bare rock behind. The health of an ecosystem will determine whether this rock becomes covered in algae, or whether it is recolonised with coral growth. Each year in November, coral spawning takes place and baby corals have a chance to make a new start in life! Beautifully coloured parrot fish are herbivorous grazers, scraping algae off the rocks to create a suitable slab onto which baby corals can settle and start construction of their intricate colonies. Depending on the species, if you spot a coral just a few centimetres in size, chances are it is no more than a year or two old.

Your Master Reef Guide Top Tip:

If you have a macro photography setting on your camera, have a play to try and capture some coral polyps – they are the coolest animals you’ll be able to go home and tell all your friends and family about, and we can guarantee 100% they’ll be there waiting to be the perfect subject for your photos on your next reef visit!

Get Snorkeling over Coral Wonderlands Today!

Get up close and personal with coral on your next Bundaberg, Southern Great Barrier Reef holiday on a day trip or overnight to our off-shore coral cays, or explore the reef within reach off the mainland. For more information and to book, see Southern Great Barrier Reef