[1] The term Zoöphyte is applied to simple polyps and compound individuals consisting of many polyps united together, as in most corals. They often branch like vegetation, and the polyps resemble flowers in form.
“On examining a piece of coral, it is seen to be full of little holes, popularly supposed to be the places for the stomachs of the animals, but this is not so, at all; the coral animal does not form a secretion around it like the mollusks,[2] but inside, between the two folds of its skin. Coral is, therefore, the bones and not the skull of the animal. As before stated, these animals work in societies or colonies, and their tendency is to repeat the forms peculiar to each species; thus we have corals shaped like a hand, like the branches of trees, like mushrooms, like a brain, with its convolutions. They grow and multiply in these societies by budding or gemmation. The side of the animal begins to bulge out, and the protuberance so formed develops into a new mouth, which soon eats and digests for itself, but does not separate from its parent. This process goes on symmetrically, and produces the variety of regular shapes just described.
[2] Mollusks are invertebrate animals, having a soft, fleshy body, which is inarticulate, and not radiate internally.
“Some distance below the surface, we no longer find these beautiful shapes, but a dense, solid, coral rock. Take for instance, the coral reefs of Florida. Beginning one hundred
WHAT THE CORAL IS.
and twenty feet below the surface, we first find about thirty feet of massive rock, then the astræa,[3] then the meandrina, [4] and about ten feet below the surface the palmata or hand-shaped coral. In the shallow mud between the reefs and the continent, there are multitudes of branching corals of the most beautiful forms, colors, and delicacy of structure. The production of coral rock is explained partly by the mechanical action of the waves, and partly by the destruction of the coral insect by the sea urchin and other animals that feed on it. The waves disintegrate the structure formed by the animal, and then roll back the coral sand, thus produced upon it, where it undergoes a process of induration in the course of time.
[3] Astræa, a coral in the shape of a star.
[4] Meandrina, a genus of corals with meandering cells, as the brain-stone coral.
“It is an interesting question how the structure ever rises above the water level, seeing that the animal which makes it cannot live out of the water. The little architects retain enough sea water to last them over until the next tide, and are so enabled to work up to the highest water-mark. Actinia have been observed all closed up on the rock at low water, and then suddenly opened like magnificent flowers, five and six inches in diameter, when the tide rose.”