What is a Coral Reef?

Kenya has a fringing coral reef. This type of reef is separated from the shore by a shallow lagoon. The reef is a natural barrier made of coral that stops sharks from coming into the lagoon so you are safe swimming. Usually you need a dhow to take you to the reef but in some areas the reef has grown so close to the shore that when the tide goes out you can walk through shallow water and reach the reef.

Coral reefs are built by animals called polyps that live in large groups under the sea. Polyps are usually as small as a pinhead but some reach 12 inches (30 cm) across. Polyps have a skeleton of hard calcium carbonate mineral on their outside to support and protect their bodies. This shell is coral. For coral to grow well the water must be clear and constantly moving. This is because coral polyps have tiny organisms that live within their tissues and make the food that nourishes the polyp. These cooks are like plants: they make food using photosynthesis so they need sunlight. If the water is clear the sunlight will reach them easily. Polyps also eat plankton tiny floating animals plants and bacteria. Since they can’t move Hashem brings their food to them. Waves constantly pass over the shallow waters that polyps live in and bring them plankton. The polyps peep out slightly from their coral skeleton but draw back in if they are disturbed by movement or possible predators. There are over one thousand different coral species and each one has a different shape. When I was a child I did a lot of snorkeling: I saw a wide range of coral: wrinkled brains cabbages table tops antlers wire strands and pillars. Whenever I got a cut from sharp coral I was careful to disinfect it to kill any live polyps. I was always afraid that of coral polyps growing in my blood! Years later I understood that a sea creature cannot grow in human blood.