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The Valuable Presence of the Coral Reefs

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Ankita loves to explore various aspects of science and is passionate about writing on topics of her interest.

Coral reefs are the most diverse and one of the most complex marine ecosystems on this planet. Covering less than one percent of the ocean’s floor, these large underwater structures are formed by the skeletons of marine invertebrates known as corals. This remarkable ecosystem is a home for invertebrates, million species of fishes and algae that either live or grow around them.

There are basically two types of coral species. One of the coral species builds reefs and is known as hermatypic or hard coral. This is done by extracting calcium carbonate from sea water to form a hard and durable exoskeleton around their soft bodies. The other type of species of coral is soft corals that are not involved in reef building. These are flexible corals resembling plants and include species such as sea whips or sea fans.

Each individual coral is referred to as a polyp. Coral polyps live on the calcium carbonate exoskeletons formed by their ancestors and also gradually add their own exoskeleton on that particular coral structure. This process continues across centuries until they become a massive feature of the marine life.

Types of Coral Reefs

Coral reefs are generally divided into three types. They are fringing reefs, atolls and barrier reefs. Patch reefs and bank reefs, though not considered to be the main types, are also important natural systems.

Fringing reefs: Fringing reefs grow seaward directly from the shore. These are the most common type of reef that we see and also are relatively young. They grow near the coastline around islands and continents. The fringing reefs are separated from the shore by shallow, narrow lagoons. The Ningaloo Reef is the largest fringing reef located in a remote area of Australia. It is also the only vast reef positioned close to the land.

Ningaloo Reef

Ningaloo Reef

Atolls: Atolls are located usually in the middle of the sea and create protected lagoons. These rings of coral are mostly formed when islands surrounded by fringing reefs sink into the sea or the sea level rises around them. In other words, when fringing reefs grow upward from a volcanic island that has sunk entirely, an atoll is formed. Thus, eventually the fringing reefs begin to grow and form circles with lagoons inside. The Great Chagos Bank in the Indian Ocean is the largest atoll in the world.

The coral reefs of the Great Chagos Bank

The coral reefs of the Great Chagos Bank

Barrier reefs: Parallel to the coastlines, the barrier reefs are separated by wider, deeper lagoons. These reefs are similar to fringing reefs in that they also border a shoreline. At the shallowest point, the reefs reach the water’s surface and form a barrier hindering navigation, thus the name. Barrier reefs are the largest among all the other coral reefs extending to hundreds of kilometres in length and several kilometres in width. The largest and the most famous barrier reef in the world is the Great Barrier Reef in Australia.

The Great Barrier Reef

The Great Barrier Reef

Patch reefs: They are isolated, small reefs that grow from the open bottom of a continental shelf or island platform. The patch reefs seldom reach the surface of the water, and they also vary greatly in size. The reefs are surrounded by sea grass or sand and sometimes may also occur between fringing and barrier reefs or in an atoll. Patch reefs are typically found at depths of three to six metres and are mostly found in the Caribbean and Pacific islands.

Patch Reefs

Patch Reefs

Bank reefs: Bank reefs are similar to patch reefs but larger in size. They are deep-water reefs consisting of linear or semicircular clusters which expand depending on the local factors. Photosynthesis is not the primary energy source for this ecosystem; thus, the bank reefs are built upward from the seafloor by darkness-loving corals. One of the notable bank reefs is the Carysfort Reef off the coast of Key Largo, Florida.

Carysfort Reef

Carysfort Reef

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The Sphere of Corals

Most of the coral reefs found today are 5,000 to 10,000 years old. They are mostly found in shallow, warm and clear water where there is plenty of sunlight to nurture the algae on which the coral relies for nourishment. Also referred to as the "rainforests of the sea", the coral reefs support about 25 percent of the marine species by providing them food, shelter and suitable places for breeding.

Coral reefs provide about $30 billion annually through food, tourism, fisheries, etc., in direct economic benefit of the people. Increased acidifications of the ocean, water pollution and improper fishing practices are some of the major causes for the annihilation of coral reefs. The reefs formed over a thousand years can be easily destroyed over a small period of time if necessary measures are not taken to save the them.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.


Ankita B (author) on August 20, 2020:

Thank you very much Brenda for your lovely comments. I am delighted to know that you enjoyed reading this article.

BRENDA ARLEDGE from Washington Court House on August 20, 2020:

Very interesting write.

The great coral reef is absolutely beautiful.

I have a few corals in my rock collection and would love to actually see them beneath the water someday.

Nice write.

Ankita B (author) on August 19, 2020:

Thank you very much Prithviraj for your kind comments. Always appreciated.

Prithviraj Shirole from India on August 19, 2020:

I was not knowing untill now about the types of coral reefs. Thanks for writing a very informative article on coral reefs.

Ankita B (author) on August 18, 2020:

Thank you very much Umesh Chandra for your comments. I am glad that you enjoyed reading this.

Umesh Chandra Bhatt from Kharghar, Navi Mumbai, India on August 18, 2020:

I learned a great deal. Thanks.

Ankita B (author) on August 16, 2020:

Thank you so much Linda for your kind comments. I am delighted to know that you enjoyed reading this article.

Linda Crampton from British Columbia, Canada on August 16, 2020:

Coral reefs are important and interesting. Thank you for sharing the information about corals and their reefs, Ankita. I enjoyed reading your article.

Ankita B (author) on August 13, 2020:

Thank you Danny for your kind comments. Yes the atolls look lovely. I am delighted to know that you have enjoyed reading this article very much.

Danny from India on August 13, 2020:

Ankita this is the article I was waiting for, types of corals reefs. Among them. I love the Atolls. As I mentioned in my previous articles comments that the Marshall islands atoll look lovely and mesmerizing..

Ankita B (author) on August 13, 2020:

Thank you very much Swati. I am glad you liked reading this article.

Ankita B (author) on August 13, 2020:

Thank you Jay C for your insightful comments. Yes there are many perspectives to climate change which needs to be looked. Your comments are appreciated as always.

Ankita B (author) on August 13, 2020:

I appreciate your insightful comments Marie. Indeed climate change is the primary cause for the changes in the reefs but some other factors are associated with it too. Thank you for reading and commenting.

Swati Khandelwal from Nainital on August 13, 2020:

Very nice and informative one

Jay C OBrien from Houston, TX USA on August 13, 2020:

Energy Companies have known about climate change and pollution for 40 years. I recently attended a lecture by an oil engineer on the subject. He said that increased technology caused global warming and pollution. If we are to save the environment, we must Reduce Human Population, or demand. This can be done by 1. Family Planning or 2. War, Famine, and Disease. Choose one.

Marie Flint from Jacksonville, FL USA on August 13, 2020:

This is a nicely written and well-organized article.

I do wish to mention that, through my spiritual studies, the natural cycles of the Earth, i.e. climate change, is the primary cause for the changes in the reefs, not so much human involvement. (We do need to be more respectful of the Earth, though.) The reefs assuredly will rebuild and return after the natural cleansing cycle has ended in 20 years or so.

Ankita B (author) on August 13, 2020:

Thank you very much Liz for your kind comments. Yes, coral reefs are threatened due to drastic climate changes and pollution.

Liz Westwood from UK on August 13, 2020:

Your article explains clearly about the variety of reefs. It's a shame that, in recent years, climate change and pollution is spoiling these beautiful and natural habitats.

Ankita B (author) on August 13, 2020:

Thank you very much Vandna. I am glad you liked reading this article. I truly appreciate it.

thoughtsprocess from Navsari (India) on August 12, 2020:

Beautiful photos. Thank you so much for sharing. Amazing article Ankita.

Ankita B (author) on August 12, 2020:

Thank you FlourishAnyway for your kind comments. I am glad you enjoyed reading this article.

Ankita B (author) on August 12, 2020:

I always appreciate your lovely comments Lorna. Thank you for sharing your experience too.

Ankita B (author) on August 12, 2020:

Thank you so much Eric for reading and commenting. I appreciate it as always.

FlourishAnyway from USA on August 12, 2020:

Beautiful photos but I also learned so much here. You covered the topic superbly.

Lorna Lamon on August 12, 2020:

Coral reefs are so stunning and a very necessary ecosystems. I was lucky enough to visit the great barrier reef in Australia when I lived there; the experience was unforgettable. I enjoyed this informative and interesting article with beautiful pictures.

Eric Dierker from Spring Valley, CA. U.S.A. on August 12, 2020:

So cool, I knew somethings here but you did a great job of teaching this subject.

Ankita B (author) on August 12, 2020:

Thank you very much Danny for your lovely comments. I am glad you enjoyed reading this article.

Danny from India on August 12, 2020:

Corals are an amazing piece in marine biology & also serve as a habitat for diverse species of fishes.

The coral reefs in the Marshall Islands is the most lovely.

Nice article Ankita.

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