The importance of Coral –
What Is Coral?

So you’ve done your first dive and have viewed first-hand, the beauty of the underwater world. You’ve been exposed to beautiful coral reefs and some colourful, tropical fish.
One of the most common questions I get asked is, what is coral? New divers are often confused. Are corals plants, animals or some beautiful type of rock.

PADI Rescue Diver

So what is coral?

Coral are actually animals. They are from the family Cnidaria, which is the same family as jellyfish and anemones. Corals get their colour from a type of plankton called zooxanthellae. These zooxanthellae live in symbiosis with corals. The zooxanthellae use photosynthesis to convert coral waste products into proteins and sugars.

This provides coral with energy, allowing them to grow and reproduce. Coral typically grows in shallow, nutrient poor waters so they depend on the zooxanthellae
for almost 90% of their nutrients.

Corals are colonies of small animals embedded in calcium carbonate shells. Coral reefs are made up ofa selection of different coral colonies. You may have noticed some coral colonies that look like boulders,table tops or even antlers. Those are all different colonies of coral growing side by side to make up a coral reef.

The Rainforests of the ocean

Coral reefs are known as the rainforests of the ocean and shallow coral reefs form some of the most diverse ecosystems on the planet. Coral reefs only make up about 0.1% of the world’s oceans, yet they provide homes for at least 25% of all marine species. Almost ¾ of the world’s reefs are found in the Indo-Pacific region. Coral reefs are the oldest, most productive and diverse ecosystems in the oceans.


More than 25% of coral reefs have been classified as vulnerable, endangered or critically endangered. Almost all coral reefs worldwide are now threatened in some way. Coral reefs protect shorelines from storm damage, provide homes for countless marine species
and drive tourism.

Invaluable benefits to mankind

Some corals are being studied to treat diseases. Coral reefs are being studied by pharmacologists studying anti-cancer and anti-HIV agents, as well as new antibiotic research. Coral attracts tourists, which generates incomes for a wide variety of businesses and boosts local economies.

Tourism is the world’s largest industry and sustains 10% of all jobs. Healthy reefs provide food, shelter, income and social stability for hundreds of millions of people.

Snorkelers and divers are natural ambassadors for the protection of coral reefs. We are in the water frequently and notice short and long term changes in the aquatic world.

The main threats to coral reefs

Coral reefs have date back thousands of years and have survived many natural changes, but unfortunately many of them are now struggling to survive due to the impact humankind is wreaking on them.

Around one quarter of coral reefs around the world are already damaged beyond repair and another two thirds under serious threat of major damage mainly due to us humans.

Major threats to coral reefs and their habitats include:

Climate Change

Corals cannot survive if the water temperature of the sea rises too high, this leads to them bleaching and dying. Global warming has led to increased levels of coral bleaching around the globe and this is predicted to increase in frequency and severity in the coming years.

Destructive Fishing

These methods that harm the reefs include cyanide fishing, dynamite fishing and pulling a net across the reefs which is known as bottom trawling.


When a species is overfished it affects the balance of the local ecosystem and warps the food chain and causing effects far beyond the directly overfished population.

Careless Tourism

Careless boating, diving, snorkeling, and fishing happens around the world, with people touching reefs, stirring up sediment, collecting coral, and dropping anchors on reefs. Some tourist resorts and infrastructure have been built directly on top of reefs, and some resorts empty their sewage or other wastes directly into water surrounding coral reefs.


Industrial and urban waste, sewage and chemicals draining are poisoning reefs. These toxins are dumped directly into the ocean or carried by river systems from sources upstream. Reefs are also at risk of nutrient pollution, this is where the ocean becomes rich in nutrients as a result of fertilizer release. This causes excess algae release which chokes
the corals of their energy source.


Mining, logging, farming and construction is leading to increased erosion and run off entering the rivers and streams. This ends up in the ocean, where it smothers corals by depriving them of the light needed to survive. Destruction of mangrove forests close to the shores is exacerbating the problem as they act as a natural ‘blocker’ for sediment.

Coral Mining

In some areas coral is removed from reefs for use in construction as bricks and cement for new buildings. Corals are also sold as souvenirs to tourists being made into necklaces and over jewelry items by exporters who don’t care about the damage done to reefs.

So how can you help protect coral reefs when you are visiting Koh Tao?

You can participate in beach clean ups and dive site clean ups. Use our recycling bins. Koh Tao has around 3 million tourists a year that produce about 30 tons of rubbish a day.
Crystal Dive Koh Tao has a bag recycling station in the bar and use metal straws. Say no to plastic bags and use our water refilling station in the office.

Crystal Dive and The Coral Tribe frequently host clean ups to keep plastic bags, and other debris from smothering coral reefs. Check our board in the bar and outside the office for more information.

You can also buy a reusable water bottle and get free refills at Crystal’s office and other water stations around the island. Choose cans or glass bottles which are easier to recycle.

If you smoke, put your cigarettes into garbage bins, not on the beach.
Sign up for an ECO dive with The Coral Tribe where you can help gather important scientific data on coral reefs.

Coralwatch is a citizen science initiative which supports global monitoring of coral reefs. It’s fun, informative and valuable program to learn more about coral reefs.

Crystal Dive leads the way in marine conservation projects on Koh Tao.

Crystal Dive and The Coral Tribe created and maintain the most popular artificial reef on Koh Tao, Junkyard. There are always things to do to help maintain this popular site. Even non-divers can participate by ‘adopting a coral’ and receive information and pictures of your adopted coral.

When diving respect the marine species that live there by not touching anything underwater and not supporting dive centres that do. Coral is invisible to the naked eye
for its first 6 months of life.

The oil on our fingers can kill coral even if it looks like it’s just a rock.

Perfect your diving skills

Watch where you put your fins and use good buoyancy skills. When we kick or stand on coral we break off pieces that have taken years to grow. Some coral species take 18 months to grow an inch! Secure all your gauges and equipment to avoid accidental contact with coral reefs.

If you haven’t dived for a while consider completing a scuba review before diving in!

If you are unsure about your buoyancy skills in general consider completing a Peak Performance Buoyancy course with a PADI Instructor. Scheduled over 1 day and including 2 dives this course won’t just improve your buoyancy, but your air consumption too, as well as your overall confidence as a diver!

Don’t use Suncream

Wearing a rash vest is the preferred way of avoiding getting sunburnt but you can apply sunscreen an hour before entering the water so it is well absorbed into your skin. Sunscreen washes off and prevents the corals from being able to photosynthesize, essentially starving the plankton from converting wastes to nutrients that the coral needs to survive.

When it comes to buying sunscreen look for one that uses natural products (organic or biodegradeable for example) as this is better for the environment. Look for a brand that uses physical sunblocks such as titanium dioxide and zinc oxide instead of chemical ones.

Think before you buy

Don’t buy jewelry with corals and shells; by purchasing them it creates an increased demand for them, exploiting the population. When left in the ocean the coral and shells break down and are used by the coral to build their skeletons. This is why no shells or coral decorate Crystal Dive’s offices, bar or restaurants.

Eat sustainable seafood. Overfishing disrupts the ecological balance by eliminating top predators and algae eating fish that are vital to keep algae growth in balance. Unchecked algae growth is coral’s biggest competitor on the Reef. Changes in fishing techniques have led to increased pressure on fish stocks and overexploitation of coral reefs. Unsustainable fishing practices affects 55% of the world’s reefs.

When snorkelling or diving, chose operators that don’t feed reef fish.Human food is not good for fish, it changes their feeding patterns, makes them more susceptible to predators and food waste promotes algae growth which can smother coral reefs. The normal algae eating fish are all full so are no longer eating the algae, enjoy fish watching without interfering.

Educate yourself

Come visit us at Crystal Dive, Koh Tao and learn more about coral reefs and how to protect them. You can take Project Aware’s Coral Reef Conservation Specialty Course which will teach you all about the plight of the world’s coral reefs. The course describes how coral reefs function and why they are so important.

© Crystal Dive Koh Tao