CORALS. 



SEA-FANS AND SEA- WHIPS. 



The animals commonly known as 

 Corals, sea anemones and polyps, have 

 been very appropriately called zoophytes 

 or flower animals from their close exter- 

 nal resemblance to flowers and also 

 from their variety of brilliant colora- 

 tion. Many species, as the sea fans, sea 

 plumes and sea whips, grow in a manner 

 so like the shrubs and trees that until a 

 comparatively recent date, they deceived 

 even the men of science. The older na- 

 turalists classified many of them as plants 

 and it was not until the middle of the 

 eighteenth century that their true char- 

 acter became definitely known. 



These animals form a part of the sub- 

 kingdom Coelenterata and in classification 

 are placed between the sponges (Pori- 

 fera) and the planarian worms. The 

 name Coelenterata is well chosen. It 

 signifies a hidden digestive tract and 

 refers to the fact that the stomach is 

 concealed in the lower part of the body, 

 directly in the center of the animal. 



The general plan of all Coral animals 

 is essentially as follows : The body is 

 rounded, cylindrical and sac-like and is 

 divided internally by partitions called 

 mesenteries, which are usually six or 

 eight in number. In the center of the 

 body, and suspended by the partitions, is 

 placed the stomach which is connected 

 with the body cavity by little openings. 

 The mouth is placed in the center of the 

 upper surface and is surrounded by a 

 circle of tentacles. The most notable 

 character of these animals is the presence 

 of stinging organs known as lasso-cells 

 which have the power of throwing out 

 little barbed bodies or nettling cells which 

 serve as a means of defense and also as 

 a means of procuring food. 



The animals comprising this branch 

 of Zoology differ widely in external 

 form. They range from the minute hy- 

 droids which encrust stones at low water 



to the heautiful stone building Corals, 

 the brilliant sea anemones and the curi- 

 ous jelly-fishes. Some are stationary for 

 life, while others swim about from place 

 to place. Some live on the surface of 

 the ocean, while others live at the bottom 

 of the sea in very deep water. With the 

 exception of a few small hydroids, all 

 are marine and the majority of these live 

 near the shore of continents and islands. 

 Typically they are tropical animals, al- 

 though a number, particularly the jelly 

 fishes, live in northern seas and some of 

 the Gorgonias live in the arctic seas at 

 a considerable depth. These animals 

 are directly of little use to> man, but in- 

 directly they have done more for him 

 than almost any other animal. The stony 

 Corals have built up islands, added to the 

 growth of continents, and their fossilized 

 remains are now used for building pur- 

 poses under the names of marble and 

 limestone. They have been engaged in 

 this work for millions of year and we 

 find their remains in the oldest geological 

 rocks. In many places, as at Cincinnati, 

 Chicago and parts of Ohio and Indiana, 

 extensive ancient reefs have been found 

 which show that this class of animals 

 flourished in large numbers in the old 

 Silurian sea. 



The subkingdom Coelenterata is di- 

 vided into four classes ; the Hydrozoa, 

 which includes such animals as the fresh- 

 water hydra and the little incrusting hy- 

 droids of the seashore; the Scyphozoa,. 

 or the jelly-fishes ; the Anthozoa, includ- 

 ing the stony corals, the sea anemones, 

 sea fans and sea plumes, and the Cteno- 

 phora, or comb-bearers, which are small, 

 rounded, jelly-like animals of peculiar 

 form. 



The class Anthozoa is divided into two 

 subclasses of which the first, the Alcyon- 

 aria, will be considered in this article. 

 In this group each animal or polyp has 



83. 



