To create a variety of caves and microhabitats to support the maximum diversity of species for teaching purposes, the rockwork in the reef tank has been built up on an elaborate framework of PVC pipes. In addition to creating caves, this makes numerous ledges and overhangs, with shaded regions underneath for sponges and other organisms that can't tolerate high light levels.
Herbivorous fish: The fish on the right in this picture is a sailfin tang (Zebrasoma veliferum). This and the blue tang (Paracanthus hepatus) in the same tank are herbivorous fish that graze algae off the rocks. Along with a multitude of small hermit crabs and snails, these herbivorous fish are essential to the stable functioning of this reef aquarium. Even in the wild, tangs, surgeonfish, and other herbivores play important roles in the preservation of reef habitats by continually grazing algae that would otherwise overtake and inhibit the growth of the stony corals that build the reef.