The Great Barrier Reef QBIR One of the seven natural wonders of the world In an ecosystem, how do living things depend on each other? Do you think it is important to preserve ecosystems? Why or why not? Great Barrier Reef facts The reef contains: 1,500 species of fish 411 types of hard coral one-third of the world’s soft corals 134 species of sharks and rays six of the world’s seven species of threatened marine turtles more than 30 species of marine mammals, including the vulnerable dugong. The Crown of Thorns Starfish The highest on the list of dangers to the Great Barrier Reef lives on the reef itself. The Crown of Thorns starfish feasts on the polyps of coral, releasing neurotoxins to absorb the tissue of the coral and literally “sucks the life” out of the reef’s backbone.(the coral) Once great numbers of Crown of Thorns starfish are grouped together, their impact of the reef can be catastrophic – if the number of over 30 adult starfish reside in a 10 m. area, it can be called an “outbreak” which is usually a result of a lack of predators (such as the Giant Triton) of the starfish within the area. Many researchers believe that the current abundance of Crown of Thorns starfish could be a result of agricultural runoff which increases the amount of algae which serve as food for the starfish. Photo © Sandra Pizarro Question: How Do Coral Reefs Form? Answer: Stony corals are a remarkable group of animals that inhabit tropical marine waters around the world and form vast colonies known as coral reefs. Coral reefs often resemble rock formations or even plants but such resemblances are only superficial. Coral reefs are in fact made up of many tiny animals known as coral polyps. Each coral polyp is an individual animal and the individual polyps coexist as part of a larger colony of polyps. Coral reefs provide habitat for an immense diversity of other organisms including fishes, marine mammals, marine turtles, and invertebrates. Stony corals inhabit marine habitats where the water is quite clear, the temperature remains within the range of 18°C-29°C A stony coral colony begins as a single free-swimming founder coral polyp that attaches itself to a hard substrate such as submerged rocks. The founder polyp replicates itself repeatedly through asexual reproduction, producing a colony. The colony consists of a base which is attached to the reef substrate, a growing edge zone (where new coral polyps are produced), and an upper surface that is exposed to light that filters down through the water. Stony corals are named because of the stone-like skeleton that forms within their bodies. This hard skeleton is made up of calcium carbonate (CaCO3) and gives a coral reef much of its structure. Over time, stony coral polyps lift up from their base and new calcium carbonate is deposited on top of the old surface. As a result, the coral grows upward on a mound of hard rock-like deposits. Polyp The beginning of coral growth Dugong: related to the manatee. Currently endangered in the area of the Great Barrier Reef. Manatee: most commonly found in Florida