Marvels of the Universe 



273 



THE OKGAN-PIPE CORAL. 



This photograph of the living coral, taken through the water, shows the polyps expanded. They are the builders of the 

 "organ pipes." which are more clearly shown in the other photograph from the dead and empty coral. The tentacles of the polyps 

 are coloured a bright emerald green, making a fine contrast with the red of the tubes, 



pillars. It is from these floors that new tubes are begun by the budding off of new polyps from 

 the older ones. 



Both the tubes and the platforms are of a striking crimson colour, the polyps themselves 

 and their enclosing flesh, with the exception of their tentacles, being of the same colour as their 

 hard skeleton. The tentacles, which are eight in number, are of a fine emerald green. When living, 

 each of the tubes encloses within it a little coral polyp, and the effect of hundreds of green tentacles 

 projecting from hundreds of crimson tubes is marvellous in the extreme. It must be remembered 

 that each polyp is essentially the same as a sea-anemone, although much smaller, and also that the 

 hundreds of rosetted polyps in a single lump of coral are all united together and form one compound 

 colony. The crimson layer of fleshy material covers the outside of all the tubes and the platforms, 

 and the hard chalky " coral " is the skeleton of the animal. It is the flesh which secretes from the 

 ocean the lime which goes to make up the coral, and imparts its own crimson colour to it ; and when 

 the tubes have departed from the upright sufficiently to allow room for another tube between them, 

 a fresh tube will commence to be built from one of the transverse platforms by a process of budding 

 from the parent stock. 



The colony is fed in the same way that a sea-anemone obtains its food. The polyps cannot go 

 in search of food, so they have to wait until it comes within reach of their tentacles. Then, like the 

 anemones, they grasp at the tiny particles of food which are wafted towards them, and the food 

 is conveyed by the tentacles to the mouth, which is in the centre of each cluster of tentacles. 

 Not the least remarkable thing in connection with these corals is the fact that all the polyps of a 

 colony are in organic connection with each other, and thus the food which reaches any one of 

 the numerous mouths goes to support the whole organism. 



The Organ-pipe Coral does not form reefs or islands as some corals do. The masses in which it 

 is found are comparatively small, usually not much more than a foot or so across ; and it is most 

 frequently attached to other corals. It is found in comparatively shallow water, in the pools at 

 the edge of the coral reef at low-water. 



18 



