by: Holly Miller & Sarah Blue Coral reef Biomes by: Holly Miller & Sarah Blue

~Coral reefs~ Coral reefs are warm, clear, shallow ocean habitats that are rich in life. The reefs massive structure is formed from coral polyps tiny animals that live in colonies; when coral polyps die they leave behind a hard, stony, branching structure made of limestone. The coral provides shelter for many animals in this complex habitat including sponges, nudibranchs, fish (like black tip reef sharks, groupers, clown fish, eels, parrotfish, snapper, and destructive crown of thorns) crustaceans (like crabs, shrimp, and lobsters) turtles sea snakes, snails and mollusks (like octopuses, nautilus, and clams). Birds also feast on coral reef animals.

Coral reef of Raja Ampat, West Papua, Indonesia Photo © Leslie Richter Nudibranch Photo © Daniel and Robbie Wisdom

*Where are coral reefs* Coral reefs develop in shallow, warm water, usually near land and mostly in tropics; coral prefer temperatures between 70 and 85 F there are coral reefs off the eastern coast of Africa off the southern coast of India in the red sea and off the coast of northeast and northwest Australia and on to Polynesia. There are also coral reefs off the coast of Florida, USA, to the Caribbean to brazil. They are also founded around the globe in warm waters. Coral can not stand temperature that drop much below an average of 18 C. this limits their habitat to waters between 23 N and 23 S latitude but while latitude is important so is the current. For instance in Florida the last reefs end around Miami even though certain coral species can be found up through the Carolinas. The same is true in Australia where the last reefs are just north of Fraser Island while a few scattered coral species can be found south in Sydney.

~LOCATION~ Coral reefs are found in clear topical oceans. Coral reefs in water from the surface to about 150 feet deep because they need sunlight to survive. The three types of reefs include fringing barrier and atolls reefs. Fringing reefs occur along shoreline of continents and island that are commonly found in Hawaii and the Caribbean. Barrier reefs are found farther offshore than fringing reefs, they occur most often in the indo- pacific and Caribbean. Atolls are a series of low coral islands surrounding a central lagoon. The largest reef in the world the Great barrier reef in Australia is longer than 1200 miles. That’s linger than the distance between Seattle and los angels.

*Types of corals* These are tow types of coral, hard and soft coral. Hard corals (like brain coral and Elkhorn coral) have hard, limestone skeletons which form the basis of coral reefs. Soft coral (like sea fingers and sea whips) do not build reefs.

~Types of reefs~ Fringing reefs – are reefs that form along a coastline. They grow on the continental shelf in shallow water. Barrier reefs – grow parallel to shoreline, but farther out usually separated form the land by a deep lagoon. They are called barrier reefs because they form a barrier between the lagoon and the seas, impeding navigation. Coral Atolls – are rings of coral that grow on top of old, sunken volcanoes in the ocean. They begin as firings reefs surrounding a volcanic island.

~Fringing Coral Reef, Red Sea~                                                                                  

*Coral reefs in danger* Many coral reefs are dying. Major threats to coral reefs are water pollution (from sewage and agricultural runoff), dredging off the coast, careless collecting of coral specimens and sedimentation (when silt or sand from construction or mining projects muddies the waters of a reef and kills coral, which needs light to live).

~Habitat~ Coral reefs need water that is between 68-82 F which is often located along the eastern shores of land. Reefs usually develop in areas that have a lot of wave action because the waves bring in food, nutrients on the reef. Reefs need calcium from the water to grow which is most often available in shallow warm waters.

*Plants* The sun is the source of energy for the coral reef ecosystem. Plant plankton, called phytoplankton algae, and other plants convert light energy into chemical energy through photosynthesis. As animals eat the plants and other animals, energy is passed on through the food chain. Reef building corals work together with microscopic algae, called zooxanthellae that lives in their tissue the zooxanthellae provide oxygen and food to the coral through photosynthesis. The coral polyp gives the algae a home and the carbon dioxide it needs through respiration. Besides zooxanthellae algae and sea grasses are the main types of plants in the coral reef ecosystem. These plants give food and oxygen to the animals that live on the reef. Sea grasses are especially important because they provide shelter for juvenile reef animals like conch and lobster.

~Animals~ There are as many different types of fish in two acres of coral reef in southeast Asia as there are species of birds on the entire continent of north America shocking isn't it? Coral reefs only make up about 1% of the ocean floor, but they house nearly 25% of life in the ocean. Animals use coral reefs either as a stopping point like an oasis as they travel the deep blue sea, or they live as residents at the reef. The coral themselves are the most abundant animals on the reef. They are tiny organisms called polyps that attach themselves to the hard reef and live there forever. The reef is like together in each apartment. Corals are closely related and to capture their prey. Corals can be a variety of colors white, red, pink, green, blue, orange, and purple due to natural pigments and the zooxnthellae in their tissues.

*Physiology on plants or animals* The essence of what makes the coral reef work is the presence of a unique symbiosis with unicellular algae called zooxanthellae. These zooxanthellae help the coral by giving the coral the by-products of their photosynthetic activity. Coral helps the zooxanthellae by providing them with an environment to live. Zooxanthellae provide the coral with their diverse colors. Without them the corals would be white. During bleaching events (conditions that stress corals such as high temperatures), corals release their zooxanthellae and become completely white.