Corals and Coral Reef Ecosystems- A Quick Guide to Marine Life


There’s a whole underwater world to discover, and sea pets provide a perfect opportunity to do just that. Among the many types of creatures you can find in the ocean, corals are some of the most interesting and unique. These animals come in many different shapes and colors, and each has its own story.

Keep reading if you’re interested in learning more about these amazing creatures. We’ll take a closer look at what corals are, what they do, and how you can care for them.

What are Corals?

Corals are marine invertebrates within the class Anthozoa that are characteristic of the warm waters of the tropics. Corals are a member of the Cnidaria phylum, which includes jellyfish, sea stars, and sea anemones. The stinging cells of their tentacles are used to capture zooplankton.

Unlike their jellyfish relatives, they create a hard limestone skeleton necessary for coral formation. They secrete calcium carbonate to form a hard skeleton, which provides support and shelter for themselves and other organisms.

what is coral

Many stony corals live in colonies made up of numerous individual polyps. Each coral polyp, also called coral organisms, is a sac-like animal with an open interior cavity at the top through which they extrude their long, cylindrical tentacles. Most corals reside permanently attached to solid surfaces such as rocks or the dead skeletons of previous generations.

Most corals contain symbiotic algae called zooxanthellae, which provide them with food through photosynthesis.

Reproduction of Corals

Reproduction of corals can be asexual, wherein the parent polyp splits to form two genetically identical offspring, or sexual, where eggs and sperm are released into the water to fertilize and develop into free-floating planula larvae. The larvae settle on a suitable substrate and begin the process of asexually reproducing to form a new colony.

Some corals reproduce asexually by releasing coral “seeds” that float in the water until they find a suitable place to attach and grow.

Types of Corals

There are three types of corals: stony, soft, and massive.

Stony Corals

Stony corals, also called hard corals, are the most common type. They have a hard skeleton of calcium carbonate secreted by the coral polyps. Stony corals can form large colonies on the ocean floor and are the major builders of coral reefs. That’s why they are called reef-building corals.

Soft Corals

Soft corals are less common than stony corals and have a skeleton made of protein rather than calcium carbonate. A soft coral typically grows in small colonies and is not as important in reef construction.

Massive Corals

Massive corals are the largest type of coral and can grow several meters in diameter. They do not form colonies like other corals but grow as a single organism.

Massive corals are also important in reef construction.

The Appearance of Corals

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The appearance of corals can vary depending on the species, but they typically have a cylindrical shape and are often brightly colored. They have tentacles that protrude from their top opening and can be used to sting or capture prey. Corals also have an internal cavity that is open at the top, called a mouth. This cavity is used to digest food and expel waste.

Where are Corals Found?

Coral reefs are found in tropical waters all around the world. The largest and most famous coral reef is the Great Barrier Reef, which is located off the coast of Australia.

The Importance of Corals

Corals are important for many reasons. Coral reefs are some of the most diverse ecosystems on Earth. They occupy less than one percent of the world’s ocean surface yet provide a home and shelter for 25% of all marine creatures, including small fish, mollusks, crabs, echinoderms, and sponges. They also protect coasts from waves and storms. Coral reefs are a major source of food for people all over the world. Coral reefs provide many benefits to humans, including food, tourism, and coastal protection. In addition, they provide income from tourism and recreation. 

Coral reefs play an important part in safeguarding coastal communities from water surges and storms. They basically act as a strong buffer and are able to slow down water flow, thereby preventing coastal erosion. Coral reefs also promote better water quality by filtering out debris which makes the surrounding water cleaner.

Coral reefs are not only vital for the health of our oceans but are also a significant source of food and income for coastal communities. It is estimated that coral reef fisheries provide US$ 5.7 billion annually to fishers worldwide. Reefs also support tourism and recreation, generating an estimated US$ 9.6 billion annually.

Why Are Corals So Colorful?

The colors of coral are caused by the zooxanthellae that live inside them. Zooxanthellae are algae that provide food to the coral through photosynthesis. The algae give coral their yellow, green, and brown colors. Coral can also be red, pink, or blue. The color of coral is affected by the type of algae that live inside it, the amount of light they receive, and the water temperature.

From Corals to Reefs

what is coral made of

Corals are major builders of the skeletal material in reefs. Coral reefs are formed over time as stony coral deposits calcium carbonate to form a hard skeleton. The skeletons of dead corals provide a foundation for new corals to grow on. Reefs can take thousands of years to form. Reefs can be found in all the world’s oceans, but they are most common in tropical waters.

Threats to Survival of Corals

Coral reefs are in danger from many threats, including pollution, sedimentation, climate change, overfishing, water temperature change, and water acidity. The decline of coral reefs around the world is a major environmental concern.

Overfishing is one of the major threats to the survival of corals. When coral polyps are removed from the reef, they cannot secrete calcium carbonate to form a skeleton. This can slow down or stop coral growth and lead to the death of the coral.

Pollution is another major threat to coral survival. Coral can be damaged by oil spills, chemical runoff, and sedimentation. Sedimentation can clog coral pores and prevent them from getting the food they need from their symbiotic algae.

Climate change is also a major threat to coral survival. Rising water temperatures can cause coral bleaching, in which the algae that live in the coral die, leaving the coral white and sterile. If water temperatures continue to rise, many coral species will not be able to survive.

What Can We Do To Help Protect the Coral Reefs?

are coral reefs animals

There are many things that you can do to help protect coral reefs. Some things you can do are:

  • Reduce your environmental impact by reducing pollution and properly disposing of waste.
  • Be conscious of how you fish and what species you target.
  • Raise awareness about the importance of coral reefs and their role in our planet’s ecology.

You can also help to protect coral reefs by:

  • Volunteering with organizations and donating money to them that are working to protect coral reefs.
  • Educating others about the importance of coral reefs.

With everyone’s help, we can make a difference and protect these amazing ecosystems!


Coral reefs are one of the most diverse ecosystems on Earth and provide many benefits to humans. They are in danger from many threats, including pollution, sedimentation, global warming, and overfishing. You can help protect coral reefs by reducing your impact on the environment, being conscious of how you fish, and raising awareness about their importance. With everyone’s help, we can make a difference and protect these amazing ecosystems!

Various research studies have been conducted to understand the oceanic environment better. Researchers collect coral reef samples from tropical water using deep-sea submersibles and analyze them. Studying corals is essential to understanding how to protect them from further damage.

People who are interested in learning more about aquatic life and creatures may enroll in marine science courses. Consider what you know about corals, and let us know in the comments below!

Cody Mitchell
Cody Mitchell is a pet lover and a passionate pet writer. He has worked as a professional writer for over 6 years, with a focus on creating compelling content for pet-related brands. His work has been featured in major publications. When he's not writing, Cody can be found playing with his two dogs (a labradoodle and a cocker spaniel) or cuddling his cat.

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