Corals and Coral Reefs: Discover Everything About These Fascinating Marine Organisms

Corals and Coral Reefs: Discover Everything About These Fascinating Marine Organisms

Author: Damir Kapustic

Dive into the entrancing world of corals and coral reefs and discover the hidden marvels beneath the ocean’s surface. Do you ever wonder why these underwater cities are one of the most diverse and essential ecosystems on earth? From their delicate designs to critical roles in marine life, corals reefs are beautiful and vital for our planet’s well-being. Unveil the secrets of the Great Barrier Reef, a natural beauty that attracts millions of visitors each year. Are you wondering about coral jewelry or why corals are indispensable in medicine? Read on to learn about unimaginable facts regarding fascinating life and great significance of corals!

What are Corals 

Corals are amazing sea creatures crucial to oceanic ecosystems. Many tiny polyps that join together as colonies make up coral colonies. Polyps are minute, soft-bodied tube-like organisms with tentacles for catching prey. Cnidaria group is a class where we can find coral species including sea anemones, jellyfish and other.

Picture of corals

Picture of corals

Coral Types

Hard Corals (Scleractinia)

The hard corals build calcium carbonate skeletons which form the structure of coral reef. These type of corals grow around 0.5-10 centimeters per year depending on species and circumstances making solid calcium carbonate structures that grow at different rates. Most reef-building hard corals have an average growth rate of 1-3 cm/year. Many small polyps make up each colony of hard coral. Their tubular bodies have mouth surrounded by crown tentacles. Most hard corals live in symbiosis with microscopic algae called zooxanthellae, which perform photosynthesis and provide nutrients to the corals.


Hard corals break down into two main groups such as Large Polyp Stony (LPS)coralssmallsand Small Polyp Stony (SPS)coralssmall.

Euphyllia spp. (Frogspawn, Hammer, Torch Coral), Acanthastrea spp., Trachyphyllia geoffroyi (Open Brain Coral), and Favia spp. (Moon Coral) are some of the LPS corals.

Acropora spp., Montipora spp., Pocillopora spp. (Cauliflower Coral), and Stylophora spp. are examples of SPS corals.

Soft Corals (Alcyonacea)

Soft corals lack a hard skeleton, but have internal spicules (microscopic needles) that provide some support. They are termed “soft” because of their texture which is more like leather than anything else. Many species of fish and invertebrates find habitat and shelter among the branches and polyps of soft corals which they also serve as food sources for other organisms thus increasing biodiversity on coral reefs and contributing to the complexity and health of the ecosystem through their presence. They capture plankton and organic particles from water by participating in coral reef food web.


Examples of Soft Corals:

Gorgonians known for their fan-like structures are common on reefs and add complexity to ecosystems.

Leather Corals have a smooth, leathery surface, can form varied shapes such as plates or branches.

Common in many coral reefs are soft corals belonging to Genus Sinularia; thus, they contribute to biodiversity as well as structure of these reefs

What Corals Eat

Most of the coral species live in symbiosis with small algae called zooxanthellae, which are found inside their tissues. These algae carry out photosynthesis and produce nourishment by using sunlight. These microorganisms share almost 90% of their photosynthetic products with the corals such as (these include glucose, amino acids as well as). This relationship allows corals to grow healthy even in nutrient- poor waters termed as oligotrophic waters.

Coral polyps also have tentacles that reach out at night to catch planktons and other small organisms. The tentacles possess stinging cells (nematocysts) which immobilize the prey .Moreover, coral captures different kinds of plankton like zooplankton (tiny marine organisms) and phytoplanktons (marine algae). In addition to this, tiny marine creatures such as microscopic crustaceans; larvae and detritus can be captured by corals.

Dissolved organic substances can be directly taken up by corals from water. They may be in form of amino acids, fatty acid among others types of small organic molecules. A few corals get nutrients directly through the surface of their polyps.

Corals trap floating microscopic organism or organic particles through their mucus and tentacles. Some forms of these corals produce a sticky slime-like substance that collects food particles through the water currents .This enclosed mass is then drawn back into the polyps where it is digested. Food capture strategies seem to vary widely among genera; but all appear to function effectively enough for this purpose because many are successful feeding generalists maintaining some degree of specialization within them at the same time .They rely on solar energy for capturing plankton through zooxanthellae and absorbing dissolved organics For example some use mucus while others use tentacles to capture microscopic organisms and other debris suspended in water.. This combination leads to a variety of feeding methods that enable corals to survive and thrive in different marine environments.

Colors of Corals

Coral species have many diverse set of colors, making them unique and appealing. The color of the coral depends on its kind, the type of symbiotic algae, environmental conditions and access to food. The natural color of corals is varied and may include green, brown, blue, purple, red, pink as well as yellow among others; this pigmentation has been attributed to a combination of factors such as natural pigments from the corals themselves ,the environment and availability of nutrients .Such wide range of hues makes them one the most attractive beings in the sea.


Can Corals Move?

Unlike other animals movement generally does not occur in coral species . But there are several ways these organisms or their parts can move or adapt.

For instance, polyps may change their location when capturing food from water by moving tentacles. This only happens slightly and serves mostly during feeding but also for protection purposes. Polyps also open and close due to stimuli like light touch or even presence of food.

The growth some coral colonies is achieved by budding new polyps from existing ones where slowly spreads over its substrate. As they grow along the substrate some colonies change position albeit over a long time. Other genera such as Xenia may “walk” across substrates through elongation but at a very slow pace.

Besides this stage is for them get to new areas because larvae known as planulae swim with cilia until they attach onto an appropriate place where they will mature into adults through metamorphosis (Wiley 2009).

Movement can also be seen among certain types such fungiidae which can shift across sedimentary base unlike those whose bases are fixed hence depending on current flow or contraction (Wiley 2009).

Coral Habitats

Various parts of the world’s oceans are home to corals, with most found in warm shallow tropical waters. Some places that have corals include:

Great Barrier Reef

Situated off Queensland coast, Australia is the Great Barrier Reef which is the largest coral reef on earth stretching over 2,300 kilometers and homes thousands of marine species.

Coral Triangle

Covering Indonesia, Malaysia, Philippines, Papua New Guinea, Timor-Leste and Solomon Islands; this area has highest number of coral species (over 600) and fish species running into thousands globally.

Caribbean Coral Reefs

Areas around Florida coast including Mexico, Belize, Cuba and Bahamas have corals in Caribbean Sea too. It is a very biodiverse and important ecosystem despite its small size compared to the Great Barrier Reef.

Red sea

Corals grow between Africa and Asia along coasts of Egypt Sudan Saudi Arabia Jordan etc. High numbers of tourists who are divers flock this place because it has clear water and many different types of corals attracting a lot of science people as well.

Corals in the Indian Ocean include Maldives, Seychelles, Mauritius, Andaman and Nicobar Islands, and the coast of Madagascar. They are rich with coral reefs and often attract tourists because of beautiful beaches as well as underwater life nurtured by high biological diversity.


Polynesia Micronesia Fiji Samoa Hawaii also has many small island areas that have significant coral ecosystems essential for the people living there and biodiversity.


Florida Keys is a national park in the United States located off Florida’s coast which hosts a score of marine lives including corals thereby making it a popular scuba diving site and an exploration destination to see what lies beneath its waters.


Even though they are not as wide-ranging nor diverse as tropical coral reefs, corals can also be found in Mediterranean Sea and Adriatic Sea. It is used for making jewelry like this red coral (Corallium rubrum) which is one of the most well-known corals in these two seas. Admittedly, these earrings are typically sold at depths between 10 meters to 200 meters below sea level. For all their obscurity and dullness compared with their polar opposites, the Mediterranean and Adriatic Seas still play a vital role in preserving oceanic biodiversity along with maintaining ecosystem stability.


Coral reefs are structures made up of colonies of corals that belong to marine invertebrates from class Cnidaria. These reefs are among the most biologically diverse ecosystems on earth due to their richness and ecological importance. Coral reefs begin as tiny individual coral colonies that attach themselves to hard surfaces such as volcanic rocks or eroded parts of seabed. When they attach themselves, they develop into polyps called planulae larvae after which they divide forming colonies.


Living corals can be seen on the surface of the reef, which is made up of tiny organisms called polyps. These small polyps secrete calcium carbonate responsible for building coral skeletons. Polyps create new ones continuously as they divide, spreading to cover colonies and thus forming layers of living corals over its surface. As the polyp grows then dies, it leaves behind its calcium carbonate skeleton. The skeletons form foundation for reef that creates dead coral layers below the live coral layer above.

Dead corals below the surface provide structural stability for the reef and allow it to grow in height and width. Dead corals offer a hard surface on which new coral may become attached and become established. Dead structures would not have been a suitable substrate for colonization by future generations of colonial polyps who make their homes out of these remains. Such dead skeletal remains form complex habitats that act as refuge places for many marine animals including fishes, invertebrates and algae among others.


Great Barrier Reef

The Great Barrier Reef is the largest coral system in the world and one of the most impressive natural wonders. It is located off the coast of Queensland in Australia, stretching over 2,300 kilometers. It covers an area of approximately 344,400 square kilometers. It consists of over 2,900 individual reefs and 900 islands. It was inscribed on the UNESCO World Heritage List in 1981 due to its exceptional natural value. 


It is home to thousands of species, including over 1,500 species of fish, 411 species of hard corals, 134 species of marine mammals, and hundreds of species of seabirds. Besides corals, the reef provides a habitat for sea turtles, sharks, rays, dolphins, and dugongs. The Great Barrier Reef encompasses diverse ecosystems, including lagoons, mangroves, estuaries, shallow waters, and deep reefs. The formation of the Great Barrier Reef began around 20 million years ago, while its current form is about 8,000 years old, after the last ice age. The reef grows through a continuous process of calcium carbonate construction by corals and other organisms, along with sediment accumulation. 

The Great Barrier Reef attracts about 2 million tourists annually, significantly contributing to the Australian economy. Popular activities include scuba diving, snorkeling, fishing, cruising, and marine life observation. 

The Great Barrier Reef Marine Park Authority (GBRMPA) enforces regulations to conserve the reef. Large portions of the reef have been declared protected areas with restrictions on fishing, tourism, and other activities. Research and education programs focus on monitoring the reef's condition and raising awareness about its importance and threats.

Coral Jewelry Making and Other Roles

Coral jewelry making dates back thousands of years and coral jewelries are considered beautiful pieces with symbolic meanings. Red coral (Corallium rubrum) is the most popular material for making jewelry because of its deep red color. It is found in the Mediterranean Sea and the Atlantic Ocean in sections. 


The trade of corals is regulated nationally and internationally by laws like CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) to prevent their over exploitation. 

Corals are used as biomaterials in medicine, specifically for bone grafting. Coral calcium carbonate resembles human bone and can induce bone formation during orthopedic and dental surgeries.

Research is ongoing on bioactive substances from corals and coral organisms to develop new drugs. For example, some coral-derived substances have shown anti-cancer, antivirus, or antibacterial activities.

Coral reefs restoration uses coral fragments. Such techniques include planting corals into damaged areas to stimulate recovery processes such as growth. Corals are also used to create artificial reefs to improve marine life habitat that will also facilitate fishing and ecotourism; they also serve as natural breakwaters along several beaches thus curbing erosion rates too.

Coral is a symbol of beauty and protection in many cultures across the world. Traditional ceremonies use coral jewelries or decorations largely made from this precious material.


Why Corals Are Important

Corals are important for marine ecosystems as well as human communities due to a range of reasons. It could be argued that their importance is viewed from an ecological, economic and cultural perspective. Coral reefs provide habitat for about 25% of all marine species including fish, mollusks, crustaceans, sea turtles, and many others.

Corals develop complicated structures that allow different ecological niches to develop supporting rich biodiversity. They are a significant portion of the food chains and support populations of several species which depend on them for food and shelter. Presence of coral reefs at coastlines reduces wave strengths hence acting as natural wave barriers to protect beaches from erosion and storm surges. Reefs also hold sediments in place preventing it from moving further shoreward.

Coral reefs form habitats for many fish species important in local or commercial fisheries during specific stages of their life cycles. Due to their beauty and biodiversity, millions of tourists visit coral reefs annually. Diving together with snorkeling have great economic impacts towards local areas.

Coral reefs are essential sites for scientific studies that help explain ecology, evolution, climate change and biotechnology among others. Corals are vital for maintaining the health of oceans and enhancing survival rates amongst many marine species globally. Their ecological, economic and cultural significance makes them indispensable in relation to maintaining biodiversity; supporting local societies; protecting shores etcetera.

Conservation and Protection of Corals

Corals face numerous threats to their survival. Climate change, which includes increased ocean temperatures and ocean acidification, leads to coral bleaching and weakens their skeletons. 

Pollution from agricultural chemicals, plastics, and oil spills also damage coral ecosystems further. Algal blooms resulting from eutrophication due to excess nutrients blocks sunlight and reduces oxygen in the water.

Coral habitats are destroyed by overfishing while ecological balance is disrupted. Coral reefs are physically damaged by human activities like tourism and land development among others leading to increased sedimentation that chocks the corals.

Marine protected areas can regulate activities around them which aids in conserving corals. Reducing pollution through proper waste management as well as employing ecological farming is key. Global efforts towards greenhouse gas reduction can help mitigate climate change.

Damaged areas can be recovered through active reef restoration programs such as coral transplantation. Coral biodiversity is vital for our planet’s future security considerations regarding shoreline protections. They play a critical role in ecosystems; without them there would be no ecosystem functioning at all. Coral conservation requires coordination because they are so interconnected with other species within their environment from which they draw sustenance. The healthiness of seas depends on the coral preservation so that productivity is assured in those areas. For worldwide societies, corals have significance.


Corals are more than beautiful marine organisms; they create life under the sea providing homes for thousands of species and protecting us against shore erosion. There cannot be enough said about how ecologically important these species are not just to themselves but also to people’s economic wellbeing or even cultural heritage. Nevertheless, we must address these myriad challenges that threaten their existence on an urgent basis as well as act-on-them right away lest our great grandchildren find nothing left. It is not only scientists or ecologists who should take care of it instead it needs everybody’s hands job including me. By doing some little things, like avoiding plastic bags and supporting eco-tourism, we can help save these fragile ecosystems. Our destiny is inextricably linked to that of coral reefs. Because they are so crucial to marine life our investment today in their protection guarantees the beauty and health of our oceans tomorrow and the years beyond.