With increasing carbon dioxide levels and seas turning more acidic, there’s a real possibility that coral reefs and the sea life that relies on them might become extinct by the end of the century. In order to prevent such an event we must know about the role they play in our ecosystem
What are corals ?
Corals are invertebrate animals belonging to a large group of colourful and fascinating animals called Cnidaria. Other animals in this group that you may have seen in rock pools or on the beach include jelly fish and sea anemones. Although Cnidarians exhibit a wide variety of colours, shapes and sizes, they all share the same distinguishing characteristics; a simple stomach with a single mouth opening surrounded by stinging tentacles. An individual coral is called a polyp. They eat small food particles and fish like plankton.
Types of corals
Coral are generally classified as either “hard coral” or “soft coral”. There are around 800 known species of hard coral, also known as the ‘reef building’ corals. Soft corals, which include seas fans, sea feathers and sea whips, don’t have the rock-like calcareous skeleton like the others, instead they grow wood-like cores for support and fleshy rinds for protection. Soft corals also live in colonies, that often resemble brightly coloured plants or trees, and are easy to tell apart from hard corals as their polyps have tentacles that occur in numerals of 8, and have a distinctive feathery appearance. Soft corals are found in oceans from the equator to the north and south poles, generally in caves or ledges. Here, they hang down in order to capture food floating by in the currents that are usually typical of these places.
The reef contains
- 1,500 species of fish
- 411 types of hard coral
- one-third of the world’s soft corals
- 134 species of sharks and rays
- six of the world’s seven species of threatened marine turtles
- more than 30 species of marine mammals, including the vulnerable dugong.
Source: wwf.org.au and icriforum.org
The Great Barrier Reef
Found off the coast of Australia is a natural wonder whose beauty can maybe rivalled only by lush green forests. However, the colours and its brilliance remain unparalleled. The Great Barrier Reef (GBR) stretches 2,300 kilometres along the Queensland coast and includes over 2,900 reefs, and around 940 islands and cays. The GBR can be seen from outer space and is the world’s biggest single structure made by living organisms. This reef structure is composed of and built by billions of tiny organisms, known as coral polyps. It supports a wide diversity of life and was selected as a World Heritage Site in 1981. CNN called it one of the seven natural wonders of the world. But like all nature’s resources, this too is facing danger thanks to human intervention. Reports are rife are the reefs maybe in danger after all. Reefs are caught in a pincer between local pollution and overfishing on the one hand, and rising temperatures and ocean acidification on the other. Reef decline is worldwide, though some reefs are adapting better than others and those remote from human activity are holding up the best.
Marine life in the GBR
- 30 species of whales, dolphins and porpoises live in, or visit Great Barrier Reef waters.
- Some of the largest populations of dugongs in the world live on the Great Barrier Reef
- Over 200 species of birds (including 40 species of seabirds) live on the Great Barrier Reef
- Six breeding species of sea turtles live on the Great Barrier Reef
- 14 species of sea snakes live on the Great Barrier Reef
- 1500 species of fish live on the Great Barrier Reef
- 5,000 species of molluscs live on the Great Barrier Reef
- 400 species of coral live on the Great Barrier Reef
- Of some 60 species of seagrass around the world, there are 30 in Australia and 15 in Queensland waters.
- 500 species of seaweed or marine algae live on the Great Barrier Reef
Importance of corals to the ecosystem
- Coral reefs are part of a larger ecosystem that also includes mangroves and seagrass beds. Mangroves provide nursery and breeding grounds for marine life, that then migrate to the reef.
- Coral reefs are home to various species of fish and so if they are destroyed they would be homeless with no place to lay eggs. Coral reefs play an important in regulating the carbon dioxide level in the ocean water. Coral polyps turns carbon dioxide in the water into a limestone shell. Without corals, the amount of carbon dioxide in the water would rise affecting all living things on Earth. The reefs also protect coasts from strong currents and waves, as it slows down the water before it hits the shore, as they provide a barrier between the sea and the shore, hence the name barrier reefs.
Fish found in coral reefs
There are four basic categories into which the fish found in coral reefs can be divided:
Herbivores: Parrotfish, suregeonfish, rabbitfish and damselfishes
Planktivores: Wrasses, snappers, sea basses, jawfish, cardianlfish, soldierfish and squirrelfish
Benthic carnivores: Butterflyfish, triggerfish, filefishes, trunkfish, puffers, trunckfish, grunts
Piscivores: Jacks ,barracudas, needlefish, and trumpetfish, frogfish, lizardfish, flatfish, groupers, and scorpionfish.
Where are they found?
- Coral reefs are located in tropical oceans near the equator.
- The largest coral reef is the Great Barrier Reef in Australia.
- The second largest coral reef can be found off the coast of Belize, in Central America.
- Other reefs are found in Hawaii, the Red Sea, and other areas in tropical oceans.