The calcium carbonate skeleton of soft corals is located within their bodies, allowing them to move with the wave action. Over 800 species of corals have been described to date. Sponges like this orange elephant ear sponge are water filters for the reef. They filter up to 30,000 times their body volume every day. Researchers are discovering unique chemical compounds in sponges and other reef species that may have important medicinal properties and other uses.
Corals are large colonies of small animals called polyps.
These polyps reside within a cup-like calcium carbonate skeleton. They have a central opening surrounded by tentacles which can be extended to feed on phytoplankton in the water column.