Did you know that coral reefs are made by animals, and that they are currently endangered around the world, mainly due to human activity? Okay, let’s start at the beginning. What are coral reefs exactly anyway? Maybe you are familiar with the white coral you often find at a bottom of a fish tank. That is coral that has been harvested from a coral reef, but it is dead. How do you know? Living coral is very colourful, but when it dies, it becomes “bleached” or white, like the coral in the fish tank. Is coral in the ocean actually alive? Absolutely. The hard structure of a coral reef is actually created by two living creatures, coral and coralline algae. The algae live inside the coral organisms. Like plants, algae carry out photosynthesis, a process where the sun’s energy is used to make food. The coral uses this food for growth and the algae have a safe home. As result, the two creatures live happily together. Both the coral and the algae contribute to the growth of the coral reef by producing limestone. Limestone is a hard stone that is rich in calcium. It is made by some ocean organisms, for example, seashells! Over the years, the reefs get larger and larger. The largest known coral reef in the world is the Great Barrier Reef in Australia. It is 1900 km (1200 miles) long!

Because coral reefs need sunshine to grow, they are only found in the top 30 m (100 feet) of the oceans. They provide a home for an amazing variety of plant and animal life under the ocean. Over 4000 different types of fish live in coral reefs. In a lot of ways, a reef is like a giant fish hatchery. For these reasons, it is important that coral reefs are protected. From whom? From humans, that’s whom! Human activity is currently threatening coral reefs around the world. The top causes of reef destruction are pollution and over fishing. Tourism (too many people diving to see the reefs) and damage from boats and explosions are also big problems. (Look up “dynamite fishing” on the Internet and see what comes up!) So is global warming. As the seas warm up and water levels rise, that spells big trouble for coral reefs. In tomorrow’s blog, we’ll look at a late breaking news story that shows how, even when humans try to clean up their act, they can destroy these amazingly sensitive habitats.