Coral Reef and different types of coral reef!

  

     A coral is a group of tiny animals called polyps living under the water. It is often seen as colorful rocks under the ocean. But actually, these are tiny animals that sit on a rigid rock made up of calcium carbonate. These rocks are called the skeletons of polyps. These corals make their whole life over there. Over time, the corals get to multiply and cause a major reef called a coral reef. As we know, the largest coral reef in the world is the Great Barrier Reef in Queensland, Australia. The corals evolved in the world some 450 million years ago, whereas humans evolved in the world only 7 million years ago.

Coral Reef

    The coral reef provides us various advantages. It protects us from natural disasters like tsunamis by buffering the ocean waves. It also acts as a home for millions of species in the ocean. Apart from these advantages, most of the human population on the seaside depends largely on the coral reef for food and medicines.  The medicines obtained from the coral reefs can cure asthma, cancer, and heart diseases. The main function of the coral reef is to absorb carbon dioxide from the ocean and transform it into calcium carbonate for building up the reef. The way the coral builds its colony is an impressive operation. Let’s look at it.

     A coral consists of thousands of polyps. Each coral has different shapes of polyps. Each contributes to building up a colony. It starts its life as a larva attaching to a rock. A polyp mainly consists of a mouth and a stomach. As it starts its lifetime, it absorbs dissolved minerals from the water through its mouth. As the dissolved minerals pass into the stomach, it is mixed with other components in the stomach to produce calcium carbonate, which is an essential thing for growing their colony. When the calcium carbonate is secreted, the polyp stands up from the rock leaving some space in the bottom. Then the polyp pours the secreted compound into the space, thus building the skeleton. Like this, each polyp secrets its own compound and tries to build the reef.

Polyp  Anatomy

Symbiotic Relationship

    But the polyp needs some energy to do this activity. This energy is given by algae called zooxanthellae, which live on the tissue of the polyp. The algae secrets its own food by the process called photosynthesis and provide Oxygen, Sugar, and fats for the polyp. The polyp in turn provides CO₂, Phosphorous, and Nitrogen for the algae to grow. Such a relationship between the algae and the polyp is called the symbiotic relationship. The color of the coral reef is given by the algae living inside them. When the salinity or acidity of the water changes; the polyps loses their algae and becomes dead. As the only main ingredient for the color of the polyp is the algae; the polyp becomes dead and white after losing its algae. This is called coral bleaching.

 

Credit (Coral Bleaching): By Vardhan Patankar - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=62822698

    These coral reefs are called off in various types depending on their forming location. These classifications are named as Fringing reef, Barrier reef, and Atoll. Let’s look at each of its classifications with a neat diagrammatic representation.

Fringing Reef:

    It is the most common type of reef seen everywhere along the coastal side. This kind of reef directly borders the land and separates the land from the sea. One of the best examples of this type of reef can be seen in Hawaii.

Fringing Reef

Barrier Reef:

    This kind of reef separates the sea from the land by a lagoon. A lagoon is a portion of freshwater that is separated from the saltwater by the reef. Some of the patch reefs can also be found in the lagoon. One of the best examples, where this type of reef can be found, is the Great Barrier Reef in Australia, which is considered one of the biggest coral reefs in the world.

Barrier Reef

Atoll:

    This type of reef does not border the land rather it borders the lagoon itself. It comes from the barrier reef. This atoll basically forms from an island (volcano island), when it sinks. As an island emerges from the sea, coral reefs get to surround the island as barrier reefs. When the island erodes over time, a small lagoon forms over, and the reef appears as a ring over that place.

Atoll