CORAL AND CORAL REEFS

Coral reefs are bursting with life in all shapes and colors. But you don't just get to see. You will find these special natural areas only under water and especially in faraway, warm countries. Still, because coral reefs are being lost without most people know it. And that while they not only beautiful, but also very useful. In this fact sheet you can read all about coral and coral reefs. Also how they are protected are protected by the World Fund.

The reef and corals

A coral reef is a natural area, just like a forest. Just as you don't have a forest without trees, a coral reef cannot exist without coral. What a tree is, everyone knows. But what is coral? That is more difficult to understand. But it is important to know what coral is if you want to understand how the coral reef - with all the

animals that live there - is put together. That's why the first part of this fact sheet is about coral.

Corals

What is coral?

You may have seen coral yourself. Some people have a piece of coral on the windowsill, for decoration. That looks like a white stone with grooves, stars and holes. But

coral, of course, is not a stone. What is? Believe it or not: coral is an animal. Or better yet, it is thousands of little animals stuck together. Those coral animals are also called “coral polyps.

. Coral as you sometimes see it on the windowsill is the skeleton of all those polyps together. Each coral polyp is attached to it and extends its tentacles into the seawater. Actually, a coral polyp is

a kind of sea anemone. Corals, like sea anemones and jellyfish, therefore belong to the nettle animals. All animals with “nettle” (stinging) tentacles with which they catch, paralyze and then eat tiny sea creatures.

Many fish find food and safety on the coral reef.

Coral and algae:

an inseparable duo

A few centuries ago, biologists didn't know what to make of corals. Were they animals or plants? They then held it to be the latter: stone plants they were called. Today we know better: corals are animals. Still, there is some truth to the plant story. Corals namely live together with very small plants. These “coral algae” are indispensable for the corals because they help build the lime house. Like all plants, the algae need sunlight. Therefore, corals grow so that their algae capture as much light as possible. The coral algae and the coral polyp both benefit from working together. The alga gets safety, sunlight and can put the waste products from the polyp to good use. The coral polyp can form the calcium skeleton and occasionally eats some algae as well.

Coral on a journey

Like all animals, a coral begins as an egg and a seed. The eggs are smaller than a pinprick and are released into the seawater by the polyps by the millions. At the same time, sperm are released into the water: even more than the eggs and much smaller. When the corals “spawn,” the seawater becomes murky. Many eggs are eaten by young fish or other marine animals. An egg that survives and is fertilized by a seed grows in a short time. Not into a polyp, but into a pear-shaped larva the size of a grain of sand. The larva can do something the polyp cannot: swim. After a few days of swimming, the larva looks for a sturdy spot and settles down. Then the larva's shape gradually changes. Within a week, it grows into a polyp with tentacles in its own constructed bowl of lime.

Polyps cuttings

Then something peculiar happens. The polyp develops bumps all around it. Each of those bumps grows into a new polyp. By “pricking” itself, a group of polyps is created. This is the beginning of a colony of many thousands of coral animals, all of which stay connected. Food is distributed throughout the colony and they also fight enemies together. But most striking, of course, is the common skeleton. The construction is perfectly matched, giving the coral its shape. Over time, a polyp dies and another new polyp is formed over the old one, with a new calcareous cup. Some colonies grow five to fifteen centimeters a year, others no more than a few millimeters.

Shapes and sizes

Corals come in unimaginable shapes and sizes. Some are branched like antlers, others form vast mats with upright protrusions; still others are mushroom-shaped or leaf-like. Famous are the brain corals: spherical in which the polyps are fused into a winding maze. And besides the familiar hard corals, there are also soft ones. Corals differ from species to species, but even within a species there is much variation. Current and especially light also affect the shape.

A soft coral up close: the polyps with their tentacles are easy to see.

Coral reefs

reef full of life

Just as trees together form a forest, so corals form a reef with each other. And just as a forest consists of more than trees, a coral reef consists consists of more than coral. Reefs are bursting with life: striking fish, but many more small, strange animals. The coral reef is an ideal place to live and “work. Many animals stay there all their lives, others come there temporarily to look for food, such as hawksbill turtles, fish from deeper water and the occasional shark or group of dolphins. Immediately striking are the colorful fish, such as butterfly fish, emperor fish, parrot fish. But

still, the reef is primarily the realm of invertebrates: sea lilies, tube worms, sponges and many others are found there in unimaginably large numbers of species.

Hidden plants

In nature, plants are very important. They are at the beginning of every food chain. The strange thing is that on a coral reef you hardly see any plants. Yet they are there. First of all, tiny algae float almost invisibly in the seawater. Also, in every spot where there is no living coral, seaweed grows. These are very thin threads that are constantly gnawed off by fish, snails and sea urchins. This makes them unnoticeable to us humans. And then there are the algae inside the corals themselves (see the box “Coral and algae: an inseparable duo”). So when you look through the corals, you actually see plants everywhere plants on the coral reef.

eating and being eaten

Many animals on the reef live on plankton: the tiny algae and animals that float in the water. Sponges, manta rays, shellfish as well as giants such as the whale shark and manta ray filter plankton from the seawater. Other animals, including the corals themselves, grab plankton from the seawater with their tentacles. And, of course, most animals on the reef are eaten again by larger animals. Only the reef shark has little to fear. Coral itself is also eaten, although its stinging cells and hard skeleton are obstacles for many attackers. A large spiny sea star, the crown of thorns, has no problem with it. One specimen eats several square meters of live coral in a year. The parrotfish is one of the few fish that eats mostly coral. It scrapes off the living layer of coral with its beak-like beak.

Different types of reefs

Just as there are different types of forests, there are also different types of coral reefs. Roughly speaking, there are three different types:

- Fringe reef: the coral reef forms a hem along the coast and borders almost directly on land. This type of reef is the most common.

- Barrier reef: the coral reef occurs in a band often dozens of kilometers off the coast.

- Atoll: the coral reef forms a sometimes very large ring in the middle of the ocean. Scattered around the world, coral reefs also differ from each other. For example, different types of corals and fish occur near Indonesia than near

Australia or near East Africa. You have to be an expert to see those differences. But even if you don't know much about coral reefs, you can see the difference between the coral reefs of the Caribbean (Atlantic Ocean off Central America) and of the Indo-Pacific (Indian Ocean and Pacific Ocean). In the former area, which includes the Antilles, there are many sea fans and other soft corals. The Indo-Pacific area, including, for example, Indonesia and the Red Sea, wins out in colorfulness and species diversity.

Nursery and meeting place

Besides food, there is more to find on the reef for many animals. Between the corals there are lots of holes, crevices and other hiding places. Ideal for all kinds of small animals. Some fish live in the open sea as adults, but come to the coral reef specifically to reproduce. This is because the young fish can grow up there safely. When they are big enough, they leave for the open sea. In turn, they will seek out the reef again when they need to release their eggs safely. There are also many animals that form an alliance with a special animal on the coral reef. For example, there is a shrimp that only occurs

between the tentacles of a special sea anemone. Some fish are almost always found between the long spines of a type of sea urchin. And so there are many more examples of animal species that depend on each other. The coral reef is an intricate network of species. All are related to each other in one way or another: as allies, competitors, prey or hunters. Only species that

specialize survive on the reef. Hence the species diversity.

Soft corals

When you think of “coral” you automatically think of “coral reef” but there are also corals that do not form calcium and therefore do not form a reef: the horn corals or soft corals. They are directly distinguishable from the stony corals, as the common, hard corals are officially called. The horn corals have a flexible skeleton and bend gracefully with the current. Horn corals greet faster than stony corals and are often more finely branched. They sometimes form large fans or bushes. And in contrast to stony corals, their polyps are often also at work during the day. Many species form a solid core of horny material, hence their name. In the case of the so-called blood coral from the Mediterranean Sea, this is orange-red in color. It has been sought after for making beads and other jewelry since the time of the Romans. The costume of a Zeeland peasant woman is not complete without a blood coral necklace. Today, blood coral has become rare throughout the Mediterranean.

Importance to humans

Food for many

Many people depend on fishing for their livelihood, and for even more people, fish is a very important food source. This is especially true in tropical countries, that is, those where coral reefs are found. Coral reefs are home to many fish, but catching fish there can only be done on a small scale. Fishing with a net is difficult on a coral reef because of all the protrusions. Also, only a limited number of fish species from the reef are suitable to eat. Still, the reef is indispensable for fishing. In fact, many fish from the open sea often spent their childhood on the coral reef. So without the coral reef, these fish could not exist. In Southeast Asia, perhaps 90% of all fish caught along the coast depend on coral reefs. Thus, the coral reef provides healthy food for millions of people.

The leopard triggerfish has an armored head that allows it to nibble from sea urchins without injuring itself.

Health for all

The coral reef is important to even more people around the world because substances are found from which medicines are made. This is because the reef's many thousands of invertebrates - snails, sponges, corals, manta rays, starfish - all need to defend themselves against enemies. Not only against fish or sea turtles, but also against fungi, bacteria or against other invertebrate animals with which they fight for one of the scarce spots. Usually, this is done by producing chemicals. Research has shown that some of these substances can be very useful as medicines. For example, a substance active against many types of viruses, including colds, flu, herpes and meningitis, has been found in the mantle Didemnum, no more than a gray slice among the coral. Only a very small fraction of chemicals in reef animals have been studied. If anywhere a cure for AIDS or cancer should be sought, it is on the coral reef.

and more...

Besides food and health, coral reefs give people even more. For example, they provide protection of the coast from wave action. This is very important especially for people in countries that do not have much money to build dikes. Not to mention, coral reefs are beautiful to see. Ideal for snorkelers and divers. This is beautiful not only for the people who live near coral reefs, but for anyone who wants to see it. Because tourists come to see the beautiful reefs, the people who live e can make money. With hotels, restaurants and by organizing diving trips.

The Coral Triangle

Of all the coral regions of the world, the Coral Triangle the absolute best. Nowhere do so many different species of corals, fish and other marine animals occur as in this little-known area: a huge triangle of sea and islands between Bali, the Philippines and the Solomon Islands. The World Wildlife Fund works at several places within the Coral Triangle to protect nature's protection. For example, WWF helps fishermen from the area to fish in such a way that the coral does not damage. With the governments of the countries in which the Coral Triangle lies, WWF agrees to declare the most important or vulnerable coral reefs a nature reserve.

Threat piece sold

Although coral reefs are unimaginably useful and beautiful, people are far from always treating them with care. On the contrary: especially in recent

years, the health of reefs worldwide is deteriorating rapidly. Sometimes coral is directly threatened. Pieces of coral, sometimes entire colonies, are wriggled out of the reef, dried, washed and go on sale. The buyers are often tourists: people who want to take home a memory of that beautiful nature. In this way, often unknowingly, they deal yet another blow to that same nature. Corals are also sold to decorate aquariums. Some types of coral are so popular that their very existence is threatened. Black coral, for example, is used to make jewelry. This species of coral has become rare in large parts of the Caribbean as a result.

In restaurants in Hong Kong, live reef fish bring in big bucks.

Fishing with poison

Other reef inhabitants such as clams, starfish and seahorses are also caught for sale. Colorful coral fish are caught to sell as ornamental fish. Most of these die within six months. Large fish are also caught alive for the aquariums of expensive restaurants in Asia. These often rare and old fish end up there on a rich customer's plate. Moreover, the catching process probably results in even more casualties. In fact, often the capture is done with a poison (cyanide). With a washing-up bottle, collectors spray a cloud of poison between the coral. When the fish come out dazed, they are caught. But other animals-including the coral itself-can die from the poison.

Anchors and bombs

Coral appears sturdy but is fragile. A net snagged behind a coral or an anchor dropped on the reef can destroy coral that has grown for decades in one fell swoop. Even greater damage is done to coral reefs by dynamite fishing. This form of fishing is used mainly in the Philippines and Indonesia. The technique is as simple as it is destructive. A bomb - often home-made - is detonated in the water, after which the dead and stunned fish are picked up from the water. Because the fish usually sink to the bottom, dynamite fishermen prefer to throw their bombs in shallow places. These are precisely the places where coral occurs. Such an explosion turns the coral reef into a mess.

Other Reefs

Not every reef is a coral reef. In fact, there are other sea creatures that attach and form chalk houses. For example, a mussel bed is also a reef. In some places there are large reefs built up by millions of tubeworms. Also, fire coral, a common coral on coral reefs, is not a direct relative of the other corals. Up close, you can see and especially feel the difference: common corals do not sting, fire coral does. In prehistoric times, several other animal groups also built reefs. Some mountains are built largely from those fossil reefs.

Where are coral reefs found?

There are a few species of coral that live in the cold deep sea and can form reefs there but most corals like warm, clear and salty water. You therefore find the usual coral reefs in seas where the water does not get colder than 20 degrees Celsius. Along the west coast of South America and Africa, cold water flows from the sea around the South Pole. Along those warm coasts, coral reefs do not occur for that reason. Also, corals need solid ground underfoot. On a sandy bottom, corals have difficulty holding on. And where there is mud, they don't feel at home at all. Especially not if fresh water is added. The fresh and muddy water from the Amazon River ensures that coral hardly ever occur off the coast of Brazil. But in suitable places, coral reefs can be dozens of kilometers long. The very largest reef is the Great Barrier Reef off the east coast of Australia. This reef totals more than 2,000 kilometers in length. All the world's coral reefs together cover an area nearly 23 times the size of the Netherlands. That seems more than it is: only a quarter percent of the surface of all seas.

Mud mess

More insidious but at least as damaging to the coral reef is pollution. Some chemicals kill reef animals. Including the coral animals themselves. But pollution can also simply be mud or sand. This can smother the coral. For example, the building of a marina can destroy coral reefs in the wider area. Deforestation also causes a lot of mud to wash out to sea. This is because the roots of trees then no longer hold the soil.

Climate and carbon dioxide

Burning coal, oil and gas releases a lot of carbon dioxide (CO2) into the atmosphere. For coral reefs, this is a big problem. First of all, because CO2 causes the earth and thus the seawater to get warmer. Corals live together with algae (see box “Coral and algae: an inseparable duo”). They are indispensable for the coral and also give it its color. When seawater gets too warm, these algae run wild. They then start producing substances that are toxic to the coral. The coral therefore rejects the algae. It then becomes pale and unhealthy. When the seawater becomes cooler again, the coral can recover. But if the bleaching lasts too long, it dies. Only the white coral skeleton then remains. Another problem is that carbon dioxide makes the seawater more acidic. If it becomes too acidic, corals can no longer make calcium shells. Thus, coral reefs suffer doubly from CO2 emissions.

If the seawater is too warm, corals fade. If it takes too long, they die and only the white skeleton remains.

To properly protect the coral reef, research is needed.

Protection Against Foul Trade.

The World Wildlife Fund is concerned with the conservation of coral reefs in a variety of ways. For example, by fighting the trade in endangered species, such as corals. Nearly 180 countries have signed a treaty making agreements on the trade in endangered animal plant species. According to that treaty, most trade in coral is now prohibited. The World Wildlife Fund co-founded the agency (TRAFFIC) that critically monitors the trade. Among other things, TRAFFIC has investigated the trade in shells and corals by Asian countries, such as the Philippines. This showed that many countries still exercise too little control.

Parks underwater

In dozens of places around the world, the World Wildlife Fund has projects to protect coral reefs. In all cases, this is done together with the population. Sometimes entire stretches of coral reefs are even declared protected areas. This has happened, for example, near Australia and off the coasts of Kenya and Mozambique. Also around the Antillean islands of Bonaire and Saba, the sea is now a protected nature reserve. Of course, there is no fence around the underwater park, but there are clear and strict rules. For example, casting anchor is strictly prohibited. Ships may only be moored to specially constructed buoys. Visitors with snorkel or scuba tanks are welcome in the natural park. But with a harpoon you are definitely not allowed.

Saving nature

On a very different scale, WWF is working to protect coral reefs through the

Colorful spectacle

Coral reefs are famous for the striking colors of fish and other animals. Those colors almost always serve the same purpose: to send a signal. What that signal is varies from species to species. In many cases it is a warning, of toxicity, for example. Especially animals that are otherwise defenseless, such as nudibranchs, successfully defend themselves this way. For many fish, it is a tool for recognizing conspecifics. Sometimes young fish have a very different pattern than the adults. This is the case of fish with a territory: the pattern of an adult fish arouses aggression, but the young can swim around everywhere undisturbed thanks to their “childlike” appearance. A very remarkable signal is given by the cleaner fish. Both with its color pattern and by a special dance, it shows who it is. Large fish from the reef will never harm the cleaner fish. In fact, they sometimes literally line up to be cleaned of parasites by this little fish and even let him swim in and out of their mouths unhindered.

Many fish from the open sea spend part of their lives on the reef. Therefore, if the coral is protected, fishermen benefit as well.

countering climate change. Actions to save energy and against energy waste are ultimately intended to prevent catastrophic consequences for nature. In addition, the WWF is committed to ensuring that less and especially more sensible fishing takes place. This requires good rules. People must also be able to see whether the fish they buy was caught in a way that does not harm nature. To this end, the WWF has worked with fishermen and manufacturers to create a hallmark. Just as wood nowadays shows whether it has been responsibly harvested, more and more fish products show that the fish has been caught decently (MSC label) or farmed responsibly (ASC label). Much is already being done to save the reefs, but there is also a lot to be done. The World Wildlife Fund will do everything possible to preserve coral reefs and everything that lives in them.