Compared to all the waters around the world, the warm waters of the tropics contain some of the richest and most diverse communities. They are only found in clear and shallow waters because sunlight is vital for them. Although they cover less than one-tenth of the world’s oceans, coral reefs are home to one-fourth of all marine species.
It may seem like a colorful paradise, but coral reefs are battlegrounds for space. Every animal from a large blue ring octopus to sea sponges need to fight for survival.
But none of the thirty-five to sixty thousand reef dwelling species would be thriving here if not for the coral. The coral reef is the foundation of all life here.
It all starts with a coral larva drifting in the open sea drifting among other reef animals. If just one of the coral larvae settles in a suitable spot and survived, a new reef will be founded. In a few days, it will change its shape forming a polyp.
During this time, it looks like a sea anemone. After identical copies bud off, a colony develops. From each polyp, a hard skeleton is formed. From this base, it begins to grow around fifteen centimeters a year. A mature reef can be thousands of years old.
As the community grows, relationships are formed between different creatures. One example of a facultative mutualism relationship is the clownfish and the anemone. The clownfish brings food to the anemone; The anemone wards off predators. It is an independent relationship because the clownfish could live somewhere else and the anemone can capture food from the water.
Some species are very dependent on each other. One example is the zooxanthellae and the coral. Zooxanthellae, a single-celled alga, capture sunlight for photosynthesis. It is provided with carbon dioxide expelled by the polyp. This provides oxygen and other nutrients the coral polyp uses to survive. The presence of zooxanthellae also provides the colorful pigments to protect the coral’s white skeleton from the harsh sunlight. Ninety-eight percent of the food consumed by the coral is produced by the algae; this shows a mutually symbiotic relationship that is beneficial to both participants.
A more negative kind of relationship is the relationship between sea stars and coral reef colonies. Crown-of-thorns-sea stars have been known to destroy entire coral reef colonies. This is a parasitic relationship in which the sea stars find food in the polyps of the coral resulting in the coral stripped to its skeleton and left to die.
Coral reefs are unlike anything else on this planet. Not only is it an important habitat for fish and other animal marine animals, but it is also an important food source for people living close to the reefs. They also act as natural barriers against storm events like hurricanes, typhoons, and tsunamis. Coral reefs need to be protected so these reefs can continue to provide a great ecosystem for these wonderful animals.