Corals and coral reef ecosystem

The ubiquitous coral reef ecosystem surrounding the Hawaiian coastline is a complex structure. It is a haven for many life forms and helps to purify water, provide food and protect the coast from sediments and storms. The corals are the lifeblood of the underwater symbiosis between different species.

People that dive and snorkel at Hanauma Bay will find literally thousands of life forms, including hard and soft corals, green sea turtles, multicolored fish of all sizes, octopuses, eels, algae, sea anemones, mushrooms, crustaceans, worms, etc. Although the coral reef is constantly growing, it faces difficulties such as human intervention for example. The branches of the corals are incredibly delicate and can be destroyed even with a little contact.

As long as we have the opportunity to enjoy Hanauma Bay, we must remember that we are only guests and we have to respect this wealth. The basic rule is watch but don’t touch!

What are corals?

The corals are a class of marine mossy organisms that exist as small polyps, usually in the form of a colony of many identical individuals. Some of the corals that release calcium carbonate to build an external “skeleton” are responsible for creating coral reefs.

Scientists will tell you that corals are invertebrates. They belong to a colorful group of animals called Meshes, their cousins are jellyfish and sea anemones. These interesting creatures are made up only of stomach and mouth, surrounded by small tentacles. Unlike plants, corals cannot produce their own food. Instead, they have small feeding weapons that are very similar to tentacles and use them to capture the food that moves around them. Unlike most animals, corals do not have visible parts of their bodies. In fact, what we call coral is made up of hundreds or even thousands of tiny coral creatures known by the not-so-beautiful name – polyp.

Each polyp has a soft body and in order to survive, it extracts calcium from seawater, which turns it into a solution of calcium carbonate, which it encloses as a shell. The solution then hardens to a limestone, and when thousands and thousands of polyps do the same and are close to each other, they merge into a coral reef and begin to resemble a huge, beautiful rock. Corals are also motionless animals, meaning that they attach to the ocean floor and end, so they look a bit like plants.

Corals also share a special symbiosis with some species of algae and often live within their tissues. Microscopic algae help corals and process their metabolic waste, using it for their nutrition – photosynthesis. Scientists estimate that the connection between corals and algae has been in existence for 25 million years. In fact, they believe that this is why coral reefs are the largest living structures on Earth, rivaling even the largest and oldest trees on our planet.

Coral bleaching

Coral Bleaching

Coral bleaching is a process in which corals lose their distinctive color as the symbiotic microalgae that live in them die as a result of changes in ocean water. Since algae supply up to 90% of their energy to many corals through photosynthesis, whitening eventually causes some corals to die. The phenomenon is mainly due to temperature changes, pathogenic bacteria, pollution and oxidation of the ocean due to increased greenhouse gas emissions into the atmosphere.