by seth » Sat Nov 23, 2013 10:08 pm
arvin
"A reef is a rock, sandbar, or other feature lying beneath the surface of the water (80 meters or less beneath low water)"
while a coral reefs are
"...underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny animals found in marine waters that
contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps belong to a group of
animals known as Cnidaria, which also includes sea anemones and jellyfish. Unlike sea anemones, coral
polyps secrete hard carbonate exoskeletons which support and protect their bodies. Reefs grow best in
warm, shallow, clear, sunny and agitated waters."
But under the context of our hobby, a reef tank or a reef aquarium is any tank that contains corals (especially reef-building corals) and other reef inhabitants like clams and reef invertebrates.
Cheers,
Marty