15 Great Facts about Coral Reefs

15 Great Facts about Coral Reefs

Colorful and stunning in all splendor, coral reefs are some of the most beautiful marine living structures in the ocean’s ecosystem. They are mostly made of hard coral, hardened by the absorbed carbon bicarbonate excreted over time by the organisms. Some are made of soft coral.  Contrary to popular assumption, corals are animals with plant-like cells, and not plants as many like to believe. A coral will consist of a polyp, or living creature, surrounded by a hard structure or exoskeleton. The exoskeleton grows over a long period to form a coral reef. These structures make up less than 1% of the ocean’s ecosystem but they support over 25% of marine life. Their importance cannot, therefore, be understated. Here’s a list of 15 interesting facts about coral reefs.

1. They’ve existed for millions of years

Image by Kanenori-Pixabay.

They’re believed to have been around for more than 240 million years, and that’s a long time. Their long life spans however do not reflect their rate of growth, which is quite slow. They take decades to cover a considerable area, but one thing’s clear, they’ve stood the test of time so far.

2. Coral reefs need sunlight to grow

Image by Shifaz Abdul-Unsplash.

The sunlight is mainly for photosynthesis, a process they depend on for food. This explains why most coral reefs are found in clear, shallow waters, where sunlight is easily attainable. However, too much sunlight can be dangerous as it can cause coral bleaching. This occurs when algae, which makes them look colorful, is expelled by too much heat, causing the coral reef to turn white. This is one of the adverse effects of global warming. Nonetheless, there are coral reefs in colder, deeper areas of the sea as well. These rely on the particles in the water for food.

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3. There are different types of coral reefs

Coral reefs come in a variety, depending on their structure, formation, and even location. The four main types based on location include the fringing reef, barrier, platform reef, and atoll.  Fringing reefs, also known as shore reefs, grow in shallow water, close to the shore. A good example is the Red Sea corals. Barriers are found near the end of a continental plate, often, where the sea bed significantly drops. An example is Australia’s Great Barrier Reef. Although rare, they have formed lagoons near the coasts of the Comoros archipelago, New Guinea, and the coasts of the Caribbean. Platform reefs grow on the continental shelf, and are often found in shallow regions. Atolls are coral reefs surrounding a lagoon, so they’re usually circular.

4. They clean up their water environment

Coral often relies on particles in the ocean for food, and when these particles are eliminated from the water’s surface, it cleans up the water. They also act as a filter system, trapping debris in the sea which makes their surrounding environment clean. For this, it’s not surprising that water environments surrounding coral reefs are usually clear, not murky or anything other than clean.

5. Over 4,000 fish species depend on coral reefs

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These structures proved fitting habitats for more than 4,000 fish species and other organisms. They have been described as ecosystem engineers or architect species since they provide spaces where other forms of life can flourish. They also provide good breeding grounds. Despite only making up less than 1 % of the ocean’s ecosystem, they support about 25% of marine life. This shows how critical coral reefs are in preserving biodiversity at sea. Coral reefs are also home to millions of species of marine flora and fauna, offering a safe and stable habitat for underwater creatures.

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6. Coral reefs stabilize the sea bed

By promoting the growth of other living organisms such as seagrasses and other sea plants, coral reefs provide more cover on the seabed, preventing the erosion of the shoreline. They also mitigate the impact of tidal surges and storms, stabilizing the seabed. Coral reefs offer a safe, protected environment for marine life that can’t survive in harsh water conditions.

7. The Great Barrier Reef is the world’s largest

Section of the Great Barrier Reef by Ank Kumar. Wikimedia Commons.

Located in Australia, the Great Barrier Reef is the world’s largest coral reef, with a size almost as big as Texas! It covers about 350,000 square kilometers, comprising over 900 islands.  It is the largest single structure made up of living organisms. It houses more than 2,900 species of coral and is one of the natural wonders of the world. It has also been designated as a heritage site.

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8. Half a billion people rely on coral reefs for food

Marine life supported by coral reefs, including the thousands of fish species, are a source of food for more than half a billion people around the world. The aesthetic feature of coral reefs is also a source of tourism, which earns countries significant income for development. Australia’s Great Barrier Reef, for example, attracts millions of visitors every year.

9. There exists hundreds of coral species

These come in all shapes, sizes, colors, and names. Brain corals, for example, resemble a human brain (hence the name), and have maze-like beautiful patterns. Sea whips appear like trees, and you could almost think you’ve found an underwater forest when they’re massive. Then there are the sea fans, which retain their soft structure, making them sway in the water like fans. Branching corals will often spread out like tree branches and pillar corals feature impressive, tall columns. A combination of all these make up some of the most iconic and beautiful marine structures.

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10. The algae growing on coral reefs makes them colorful

Image by SGR-Unsplash.

One of the ways in which corals feed is through their symbiotic relationship with microscopic algae called the zooxanthellae. These are photosynthetic organisms and hence utilize sunlight to make food. The nutrients produced are shared with the coral living organism, that is the polyp, in exchange for protection. The algae are in different colors, and they can change color depending on temperature and light conditions. This explains the colorful appearance of coral reefs. Those that grow near the surface are more colorful.

11. Surprisingly, coral reefs flourish in strong currents

Image by Francesco Ungaro-Unsplash.

Generally, it’s uncommon for organisms to thrive in areas susceptible to strong currents. This is because such areas are low on the nutrient supply necessary for survival. It’s a puzzling phenomenon, therefore, that corals would thrive in such areas, giving rise to Darwin’s paradox. Coral reefs however recycle nutrients quite easily in a closed biosphere. This ensures that every organism or form of life living within a coral reef system is well-fed.

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12. Corals have medicinal value

Ancient civilizations have proven the use of corals for medicinal purposes, and the same is true in modern times. In India, for example, the coral clax was used to treat bone disorders and imbalances in metabolism. Presently, coral shells have been sued in bone grafting and the treatment of various symptoms of cancer. Coral is also used in physiotherapy.

13. Coral reefs offer coastal protection during hurricanes

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Studies have indicated a correlation between the presence of coral and the level of coastline protection in a region. It was established that areas with coral reefs were least damaged during the series of hurricanes that hit the Eastern coastline of North America and the Caribbean in the 2000s. Coral reefs act as breakwater structures, and usually, the water inside a lagoon is calmer than the water outside the reef.

14. They are one of the slowest-growing structures on earth

It might take thousands of years for a reef to form over an expansive area. A coral can grow up to only 0.25 inches a year, making its growth rate one of the slowest for any species on earth. It is thus no surprise that their life span is quite long. Factors such as where the reef is located or the water conditions around it may determine how fast it grows.

15. They can grow only up to a certain water depth

Coral requires optimal conditions to survive, hence factors such as nutrition, temperature, and light will often determine their growth. An overarching factor is water depth. The latter has a bearing on access to sunlight and the availability of sufficient oxygen essential for survival. Corals will therefore often be found in regions with low water depth, where the sea bed is a few meters below the surface.