24 DEEP-WATER CORALS. 



The corals that we are familiar with have been bleached, 

 but when taken from the water they are of various shades 

 of olive and brown. 



Single-Polyp Corals. The Fungia, or Mushroom- 

 Coral, often attains a length of twelve inches, and is a sin- 

 gle polyp, in which the radiating septa are plainly seen. 

 They are the commonest forms of the greater depths ; ten 

 genera live in water a mile deep, four at nearly two miles, 

 while the Fungia symmetrica has been found in from one 

 hundred and eighty feet to three and a half miles of water. 

 The Caryophyllia is a common form in the Mediterranean. 

 Some are luminous. 



Branch-Coral (Madreporid(z} T T\\z Branch or Tree 

 Coral of Florida (Fig. 23) is a familiar example, and the 



FlG. 23. Madrepore. Dead and living branch. 



sides of deep channels in the reef bristle with it, the coral 

 growing in perpendicular walls and covering the reef in 

 vast patches, affording protection to myriads of animals. 

 The Leaf-Coral spreads out in great leaves several feet in 

 width. The Branch-Corals grow seven or eight inches a 

 year, contrary to general belief. 



Porites. These polyps are extremely minute, having 

 twelve short tentacles, and form large oval heads, weigh- 

 ing many thousand pounds. Many die in the center, and 

 become hollowed out like gigantic vases, and are pene- 

 trated with worms, that, when expanded, resemble flowers 



