ABSTRACT
The shrub-like form of many corals, their lack of movement, and the absence of any apparent animal life certainly confused many early biologists. The corals about which we have been talking so far, that are those with sizeable white calcareous skeletons, may be more precisely defined as the hard corals or Scleractinia. In addition there are to be found on coral reefs the soft corals, stinging corals, black corals, and sea-fans or gorgonians. The hard corals are in fact very closely related to the sea-anemones and may be looked upon as being colonial sea-anemones which secrete a hard calcareous skeleton beneath them. The living part of the coral colony consists of a thin layer of animal tissue composed of numerous tiny anemone-like individuals joined together side to side and covering the surface of the coral skeleton which they have secreted. There are a few hermatypic corals which like the cup corals have a skeleton consisting of a single corallite.
