Inhabitants of Coral Reefs

Coral reefs are sometimes called the rainforest of the ocean. The coral reef and the diverse numbers of sea creatures that inhabit or live near them comprise a much larger ecosystem. The corals themselves along with other cnidaria, molluscs, fishes, algae and worms all form a community that depends on each other for protection and food. Coral reefs require photosynthesis for survival and thus form in shallow, clear water.

  1. Cnidaria

    • The actual coral animals that make up the coral reef, along with jellyfish, sea anemones, hydras and sea whips, sea pansies and sea fans belong to the phylum Cnidaria. Cnidaria come in two basic forms: polyp form, as seen in the coral animals and sea anemones and the Medusa form, typified by jellyfish. According to the United States Environmental Protection Agency (EPA) corals live in colonies made up of many individual polyps; these polyps secrete calcium carbonate that build up the base or "reef" of the colony. Besides the coral themselves, other cnidaria such as sea whips, sea hydras and jellyfish inhabit the living forest called the reef.

    Algae

    • The corals encrusted within the reef have a symbiotic relationship with algae called zooxanthellae. The algae live inside the polyps and perform photosynthesis, thus producing food for the coral colony.

    Sponges

    • Various sponges inhabit the coral reef ecosystem. They provide shelter for fish, shrimps, crabs and other small animals.

    Worms

    • Worms, such as flat worms and polychaetes inhabit the coral reef. Flatworms live in crevices in the reef while polychaetes dig holes into the coral skeleton.

    Sea Stars

    • The crown-of-thorns sea star inhabits the reef and preys on the coral polyps that make up the reef. The crown-of-thorn sea star has the ability to devastate a coral reef and leave nothing but the calcium carbonate skeleton behind.

    Crustaceans

    • Shrimps, lobsters, crabs and other crustaceans find protection in the crevices and holes of the coral reef. Some of the crustaceans in the reef also prey on other reef animals. The coral crab preys on sea urchins and clams.

    Molluscs

    • Octopuses, squids, scallops, clams, nudibranchs and marine snails all live in or near the coral reef. Many of these animals filter food from the water for feeding while some, like the carnivorous snails, eat other molluscs and shelled animals.

    Fish

    • A very important part of the reef ecosystem comes in the form of fish. Some types of sharks, skates and rays inhabit or live near the coral reef. Additionally, parrotfish eat the hard corals on the reef while wrasses clean other fish that "dock" along the coral reef. Other fishes that inhabit the reef include eels--one of the reef's top predators--angelfish, butterflyfish, pufferfish and grouper.