§ Coral reefs are made of the skeletons of coral animals
o Coral animal is a polyp like animal with a calcium carbonate skeleton
o They form over thousands of years
§ Coral animals are relative of jellyfish
o Most are smaller than your finer nail
o They grow in shallow tropical water
o They live on algae that grows in their bodies – symbiotic relationship
o Coral animals absorb calcium from the ocean water. It combines with carbon and oxygen to form the mineral calcite
o When coral animals die they leave behind their skeletons – as they pile up a coral reef is born.
§ Limestone reefs – All coral reefs are organic limestone.
o Limestone deposits that began as coral reefs provide evidence of how plate motions have changed Earth’s surface.
o Deposits of organic limestone in areas that are dry prove that at one time that land was covered by oceans.
We have many
limestone deposits in
§ Why are they important
o They are important because they form the habitat for many larger animal species