What Are Corals?
CORAL ARE ANIMALS
While they may look like underwater plants, corals are actually animals, closely related to jellyfish and anemones. With fossils dating back to the Cabrian period 500 million years ago, they are one of the oldest animal species on the planet.
We can divide all corals into two categories:
Hard Corals have an exoskeleton of calcium carbonate, appearing solid and rock-like.
Soft Corals which do not have an exoskeleton, appear more fluid and plant-like. Both are made up of thousands of individual coral creatures, called polyps, which grow together to form colonies.
Individual polyps are extremely small - on average, there are 10,000 of them in every square meter of coral – and naturally clear. They get their color from microalgae, which exists symbiotically with the polyp, providing the coral with energy via photosynthesis.
Corals Form Reefs
With reefs taking such a long time to grow they are highly sensitive to damage.
Thanks to their hard calcium carbonite exoskeleton, hard coral colonies can continually grow on top of one another, providing a sheltered underwater habitat for soft coral, fish, and other marine life. This is why hard coral is often known as reef building coral, as it builds up the base of the reef.
Corals grow slowly, at just 0.3 to 2cm per year on average. It would have taken between 100,000 to 300,000 years for the Cozumel reef (and the larger Mesoamerican Barrier reef) to grow.
In this period, as corals die the calcium carbonate in their exoskeleton is compressed, becoming what we call “coral limestone”. This limestone formed not only the island of Cozumel but much of the Yucatan Peninsula. This entire land ecosystem and its unique topography only exists due to the remains of ancient corals.
Cozumel’s underwater limestone cliffs provide a unique base for the reef. Different corals need different amounts of sunlight, and the system of descending cliffs and ledges provides space for a variety of different species. As a result, Cozumel boasts one of the most diverse reefs in the world, home to 35 endemic species.
Coral reefs have been called the rainforests of the sea as they make up less than 0.1% of the entire ocean but 25% of all marine life depends on them.
The reef around Cozumel has protected and provided for the inhabitants of the island since the Mayan age.
The limestone and coral formations protect the island from storms and tsunamis, while providing rich fishing grounds that historically fed much of the island. Today the majority of the island’s industry revolves around tourism, with snorkelers and divers exploring the reef.
Just as the reef supports the island, the corals support the reef. The microalgaes living in coral polyps release and recycle nutrients/nitrates in the water that allow the reef to support marine life. In fact, Corals are so good at recycling nutrients, that it’s the reason the water around them is so clear!
But with increased tourism development, cruise ships, and the population growth, pollution & untrained divers that come with it harming the reefs.
Corals have also been found to produce chemicals that can be used in medicine to treat cancer, arthritis, human bacterial infections, Alzheimer’s disease, and heart disease.
80% of Cozumel Coral Reef has died in the past 40 years. Without urgent and immediate action taken, the entire reef could be gone by 2050.
It's imperative that tourists take opportunities to educate themselves on the damage they can cause and ensure that they are helping and not harming this incredible ecosystem that does so much to protect us.