Coral Reefs: Where are They Found, How are They Formed, and What Can we do to Protect Them?

Coral Reefs are diverse ecosystems formed under tropical waters that contain so many interesting types of fish, invertebrates, and other marine life such as sea turtles, sponges, and seahorses. In fact, coral reefs, or as we like to call them, “rainforests of the sea,” are home to almost one-fourth of the total species living in the sea. But did you know that coral reefs are actually alive? In honor of Earth Day this year, dive into the wonders of coral formation with us, and learn how you can protect these beautiful underwater paradises!

Coral Reefs

How are Coral Reefs formed and Where are Coral Reefs Found?

Coral reefs are divided into three types: Fringing reefs, Barrier reefs, and Atoll reefs which all require specific conditions to thrive, including shallow water, plenty of sunlight, and of course, free-swimming, reef-building corals larvae. As the coral grows over long periods, they form into a reef. The three types of reef represent different stages in the reef development over time, and each is found in different parts of the coast. 

Fringing Reefs
Coral larvae are made up of tiny organisms called polyps that secrete skeletons made of limestone, also called calcium carbonate. The secreted calcium carbonate sits on top of rocks and provides a home for more polyps to attach themselves. As the polyps live, reproduce, and die, they leave their skeletons behind. More and more polyps attach to the calcium carbonate and layer over time, bordering the coastline around islands and continents. This is the first stage of coral formation, called Fringing. It is also the most common and is considered to be the youngest of the three types of coral reefs. Other organisms with calcareous skeletons also add their remains to the reef as they die and sink.

Barrier Reefs
The second most common reef is the Barrier reef, which gets its name from the shallower coral that sticks out of the water and creates a barrier-like structure, separated from the land by a large lagoon. One of the most famous and most extensive barrier reefs is “The Great Barrier Reef,” which stretches more than 1,400 miles off the east coast of Australia. Similar to Fringing Reefs, Barrier Reefs also border the shorelines but at a much greater distance.

Atoll Reefs
As the coral grows further, it becomes heavy, pushing the sea rocks underneath. The reef then moves into the Atoll phase, where it forms a circle-shape near sea surfaces. They get their shape from growing on top of rocks, underwater islands and sometimes even on inactive volcanoes. Because of this, you can find these types of reefs in the middle of the sea. A great example of an atoll reef is the Lighthouse Reef in the Caribbean Sea. One of the most incredible things about Atoll reefs is that there can be over a million aquatic found living in these reefs, compared to an earlier stage of reefs, and depending on their size, atolls can take from 100,000 to 30,000,000 years to form fully.

How Can I Protect Coral Reefs?

We are at a dangerous turning point in our ocean's history. Coral reefs can no longer keep up with the speed of global environmental changes caused by humans. Pollution, overfishing, rising sea levels, climate change, and invasive species, amongst other local pressures, add stress on coral reefs. 

In fact, we have lost more than half of the world's coral reefs in the last 30 years, and without swift action, all shallow-water coral reefs are projected to vanish by the end of this century. While there is no way to know how severe the consequences would be of losing all of our planet's coral, around 70% of the Earth's oxygen is produced by the ocean. Coral reefs are a critical part of the balance of life in the sea, and losing these reefs could mean damage to coasts, shorelines, homes, and businesses.

But fear not, studies have shown that a healthy reef can better withstand bleaching, can recover from hurricane damage, and is better able to cope with disease outbreaks. Tropic Labs proudly sponsors the world's largest reef restoration organization based out of Key West, Florida. To date, they have farmed and planted over 100,000 corals in the Florida Reef Tract. A portion of every Tropic Labs sale is contributed to the Coral Restoration Foundation's crucial mission to educate and restore coral reefs.

Learn more about the Coral Restoration Foundation here!


  • Students, Keene State College, and BIO 381 Tropical Marine Biology. “Reef Types and How Coral Reefs Are Formed.” Go to the Cover Page of A Student's Guide to Tropical Marine Biology, 
  • “Learn More: How Are Coral Reefs Formed?” Encounter Edu, 
  • US Department of Commerce, National Oceanic and Atmospheric Administration. How Do Coral Reefs Form: Corals Tutorial, 1 June 2013,,%E2%80%94%20fringing%2C%20barrier%20or%20atoll.


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