Coral Reefs:

In this world, there are many wonders of nature, whether they are above the ground, below the ground, underwater, in the sky, or even in space. One such marvel is Coral Reefs, often unknown to many because they exist underwater. Coral reefs are found beneath the ocean surface and are referred to as the rainforest of the oceans. They are crucial for ocean ecosystems and marine life. Before delving further into their significance, let’s understand what corals actually are.


Corals are living organisms; they are invertebrates, meaning they lack a backbone, and they are cold-blooded. They belong to a group of fascinating and colorful animals called Cnidaria. Corals are part of this group, and they exist in large numbers, forming colonies of hundreds to thousands of individuals. Each individual animal in this group is referred to as a polyp, and similar to how genetically identical individuals in a human family are called family members, genetically identical groups of these polyps are termed colonies.

They form colonies in such large numbers because of a process called budding, where each original polyp continually produces copies of itself, leading to the eventual formation of colonies numbering in the hundreds to thousands. Referring to coral reefs as rainforests does not imply they are plants, as mentioned earlier, they are indeed animals. Just as rainforests are crucial for human life, coral reefs are essential for marine life to thrive, earning them the title of “rainforest of the ocean.”

Zooxanthellae are tiny algae, and corals have a mutualistic relationship with them. In this partnership, corals assist the algae by providing necessary elements like sunlight for photosynthesis. In return, Zooxanthellae contribute organic products to corals and play a significant role in the vibrant colors displayed by the corals.

Types of Corals:

Corals are found in two types, hard corals and soft corals.

Hard Corals:

The skeleton of hard corals is made of calcium. They live in colonies, and there are approximately 800 known species of hard corals. The ones that build reefs are also called hermatypic corals, and they are often referred to as Stony corals.

Soft Corals:

These corals are quite soft because they lack calcareous skeletons. They do not build reefs, and they are known as ahermatypic corals. They have a feathery appearance and, like hard corals, also live in colonies.

Coral Reefs:

Corals contain carbohydrates obtained through a symbiotic relationship with zooxanthellae. What happens is that corals attach themselves to sedimentary rocks and create a hard structure known as a reef. In simple terms, millions of polyps join together, forming strong, solid structures that make up reefs. These are unique living formations visible even from space. They are found worldwide in oceans, whether in shallow or deep waters, but they are predominantly present in tropical oceans.

Coral reefs cannot survive in either highly saline water or excessive freshwater. Therefore, they are not found in deep waters or near the surface. The reason is that deep water tends to have higher salinity, while the mouths of rivers introduce freshwater, creating conditions unsuitable for coral reef survival.

Exactly, coral reefs cannot survive in deeper waters because they require sunlight, which is limited at greater depths. This is why coral reefs are typically found at depths of up to 250 feet, beyond which they struggle to survive.

Sea waves play a crucial role for coral reefs, as these waves help provide them with essential nutrients and food. The motion of the waves facilitates the transport of nutrients, contributing to the health and sustenance of coral reefs.

Types of Coral Reefs:

Coral Reefs are found in three main types which are following;

Fringing Reef:

The most common type of reef, found along the shores of the ocean, is known for its steep and vertical slope toward the ocean. These reefs grow directly from the shore, earning them the name “shore reefs.”

Barrier Reefs:

These reefs are found parallel to the coastline and represent the highest, widest, and largest type of reefs. They are located at a distance from coastal areas.


Atolls are oval-shaped reefs found in warm tropical oceans. They are situated in the middle of the ocean.

Coral Bleaching:

Coral bleaching occurs when vibrant and colorful coral reefs begin to fade and turn white. This phenomenon occurs when the warm ocean water temperatures prompt corals to expel the algae that give them their beautiful colors. If the water remains warm for an extended period and the corals do not regain the algae, the corals may die.

Causes of Coral Bleaching:

Several factors contribute to coral bleaching. Firstly, warm temperatures play a significant role. While corals thrive in warm temperatures, an increase of just 2°C beyond their optimal range can trigger coral bleaching.

Secondly, extreme low tides can expose corals directly to sunlight during low tide events, leading to bleaching due to the intense sunlight and UV rays.

Another factor is bacterial diseases. Since algae reside in coral tissues, any disease spreading in the ocean can affect the microscopic algae, resulting in coral bleaching.

Importance Of Coral Reefs:

Coral reefs are crucial for marine life, forming a marine food chain similar to the terrestrial food chain on land. The health of marine life is directly linked to the health of coral reefs – the healthier the coral reefs, the better the marine life.

Coral reefs play a significant role in boosting the economy of a country through tourism. Locations with coral reefs attract visitors from afar, contributing to the local economy.

Moreover, coral reefs serve as natural barriers, safeguarding coastlines from the warmth of the ocean and its associated impacts.


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