THE STONY CORALS. 



The Stony Corals are of almost endless 

 variety in form and character and more 

 than 2,000 species have been described. 

 Some of these species live solitary lives 

 while others form huge colonies which 

 build whole islands by the accumulation 

 of their stony supports. Some are very 

 large while others are of small size. 



Anyone who visits the seashore may 

 easily become acquainted with a first cou- 

 sin of the Coral polyp, the sea anemone, 

 which is really a Coral animal without a 

 stony support. These animals are placed 

 in the order Zoantharia of the class An- 

 thozoa. The name of the order is from 

 two Greek words and signifies flower ani- 

 mal and the student who gives these beau- 

 tiful creatures the study which they de- 

 serve cannot fail to be impressed by their 

 close resemblance to flowers, not only in 

 their form but also in their varied colors, 

 which rival those in any of the blossoms 

 of mother earth. The sight of a vast 

 field of sea anemones with their brilliant 

 colors, graceful bodies and waving ten- 

 tacles is one not easily forgotten. 



The sea anemone being the type of this 

 class of animals a description of it may 

 not be out of place. The body is sac 

 like, or cylindrical, the base is somewhat 

 spread out and is attached to a stone or 

 other foreign object. The disk or upper 

 end supports a row of tentacles of which 

 there may be as many as two hundred, 

 arranged in multiples of five or six. The 

 internal organs consist principally of the 

 stomach which is placed in the center of 

 the body near the base. The body cavity 

 it divided by partitions or mesentersis, 

 which form a series of compartments. It 

 is to these partitions that the reproduct- 

 ive organs are attached. The Coral polyps 

 are essentially the same in structure as 

 the sea anemones, with the addition of 

 the ability to form a stony base or sup- 

 port composed of carbonate of lime. The 

 mesenteries of the polyp are reproduced 

 in the stony base and are known as septa. 



In those Coral polyps which live solitary 

 lives, as the fungus corals, the body is 

 similar to that of the sea anemone, but 

 in those species which form a colony, 

 each polyp seems to project or bud out 

 from a mass of animal matter which cov- 

 ers the stony support. Some of the sea 

 anemones are capable of very slight loco- 

 motion, but the Coral polyp is a fixed ani- 

 mal, after leaving the larval condition. 



Although apparently very sensitive, 

 the animals of this class are destitute of 

 a distinct nervous system, the nervous 

 tissue being confined to a few nerve cells 

 at the base of the tentacles. The con- 

 traction of the tentacles and disk is due 

 to two sets of powerful muscles, one ver- 

 tical and one horizontal, which pull the 

 mass together. Each tentacle is also re- 

 tracted by two sets of muscles. The 

 tentacles are hollow and the process of 

 expanding them is simply that of filling 

 them with the fluid in the body cham- 

 bers while their contraction is a reversal 

 of this process. It has been found that 

 some sea anemones possess a slight sense 

 of smell. 



One of the most remarkable and inter- 

 esting characteristics of the sea anemones 

 and Coral polyps is their power of throw- 

 ing out nettling or stinging organs 

 which paralyze their prey. These or- 

 gans are in the form of long, coiled fila- 

 ments placed on the edge of mesenterial 

 partitions and situated between those 

 mesenteries forming the walls of the 

 b'ody chambers. Unlike -the partitions, 

 they reach only a part of the way across 

 the chamber, and are especially designed 

 to support these stinging organs. These 

 nettling organs or barbs are ejected 

 through the mouth, tentacles and small 

 openings in the sides of the animal. They 

 consist of a long coiled filament ending 

 in a peculiar barb-like projection, and 

 from their fancied resemblance to a lasso 

 they have been termed lasso cells. 



Although these nettling organs are 



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