Biological Diversity and Economical Value Coral reefs are biologically very diverse ecosystems, as diverse as tropical rain forests. The reef's structure provides shelter to a wide range of organisms like fish, crabs and invertebrates. Furthermore, wave action and different organisms, in search of food and shelter, attack the whole structure. Fragments of different sizes results ranging from blocks to fine mud which then accumulates within the reef, shifted to calm areas by waves or currents. This accumulation of sand and mud provides habitat for sea grasses, blue green algae and mangroves found close to the shore.
Sea grasses form an important part of the vegetation to be found on coral reefs.
They tend to grow in sheltered places on the reef flats or in shallow water in between land and fringing reefs. Sea grasses are not algae but proper plants with roots and tiny flowers that bloom under water. Pollen is carried from the female flowers to the male ones by currents. They provide ideal shelter for a number of marine animals, and as such they are very important, but few animals feed on sea grasses. Coral reefs are also very productive ecosystems.