There are over 100,000 different animal species living in the coral reefs
Sea Stars are also known as "starfish." Scientists have come to realize the need to change the name, because a starfish is not actually a fish. Sea stars are more closly related to sea urchins and sand dollars. Sea stars are found all over the world's ocean floor. There are about 2,000 species of sea stars, some even have 10-20 arms, instead of the more common five. Sea stars do not have any blood or a brain in their bodies. Their nervous system is spread throughout their arms. Ocean water is used to push nutrients throughout their body.
Sea Urchins are spiny invertebrates about three inches in diameter. Their diet consists of algae and decayed matter. Their spikes are usually green when they are young, but change to purple later in their life. Their spikes protect them from predators and are also used to spear food.
Fish are a huge part of the coral reef ecosystem. There are over 4,000 different species of fish living in coral reefs. Many fish have adapted overtime to life in the coral reefs. Some fish, like butterflyfish eat the polyps in coral. Their mouth is small and round, and filled with little teeth to grab at the animals. Other fish, like parrotfish eat algae; they have mouths that act like scrappers to get at the algae on the rocks. The beautiful colors of the fish, and the beautiful colors of the coral, combine to make an amazing underwater world.