Coral Types
Stony Corals
often called hard corals, are
the basic building blocks of tropical coral reefs. These animals (polyps)
secrete calcium carbonate to form hard skeletons that provide protection
for their soft, delicate bodies. In tropical waters, most species
grow in colonies, joining their skeletons to produce a substantial
structure. Colonies increase in size by asexual budding of additional
polyps and successive generations overgrowing one another.
Soft Corals
So named because they do not produce hard skeletons,
soft corals also inhabit many reefs. Because they are not supported
by hard skeletons, soft-coral colonies are much smaller and more delicate
than stony corals. Also, unlike stony corals, soft corals do not need
sunlight in order to develop properly. As a result, their colonies
are often found in deeper parts of a reef.
Gorgonians
These are another type of coral living in many
reefs. Like soft corals, gorgonian polyps lack hard, outer skeletons;
however, they do have flexible internal skeletons. This enables their
colonies to develop long, thin branches that look like delicate fans
or feathers.