Caribbean Coral Reef

Physical Environment: Corals need warm water of at least 20°C but less than 30°C. They are also limited to the euphotic zone, where light penetrates. Sunlight is important because many corals harbour symbiotic algae, or dinoflagellates, that contribute nutrients to the animals and that require light to live.  Location: Coral reefs exist in warm tropical waters where there are solid substrates for attachment and water clarity is good. The largest coral reef in the world is the Great Barrier Reef off the Australian coastline, but other coral reefs are found throughout the Caribbean Sea and Pacific Ocean.  Plant Life: Dinoflagellate algae live within the coral tissue, and a variety of red and green algae live on the coral reef surface.  Animal Life: An immense variety of microorganisms, invertebrates, and fish live among the coral, making the coral reef one of the most interesting and species-rich biomes on Earth. Probably 30%–40% of all fish species on Earth are found on coral reefs. Prominent herbivores include snails, sea urchins, and fish. These are in turn consumed by octopus, sea stars, and carnivorous fish. Many species are brightly coloured, warning predators of their toxic nature.  Effects of Humans: Collectors have removed many corals and fish for the aquarium trade, and marine pollution threatens water clarity in some areas. Perhaps the greatest threat is from global warming and climate change. Water temperatures that are too high (over 30°C) can cause coral bleaching.