112 



CORALS 



vivipannis. It is possible also that it clifters trom the other 

 species in being sometimes hermaphrodite. 



These are points, however, which are still in need of 

 further careful investigation. 



TuBiPORA. — An Alc\-onarian coral that has a very wide 



geographical distribution in 

 shallow tropical sea-water is 

 the well-known Organ-pipe 

 coral [Tiibipora musica). The 

 popular name was first given 

 to it by Tournefort in 1719, 

 and has reference to its con- 

 struction by a number of 

 cylindrical tubes arranged 

 almost parallel with one 

 another, and bound together 

 by a series of transverse 

 plates or platforms, so that, 

 viewed in section, there is 

 some resemblance to the 

 arrangement of the pipes of 

 a great organ (Fig. 51). 



It is found alive, attached 

 to shells, corals, or stones, on 

 the reefs of many of the 

 shores of the Red Sea, Indian 

 Ocean, the tropical Pacific 

 Ocean, and the West Indies ; 

 and the dead corals are cast 

 up on to the beaches of some 

 of these shores in countless 

 numbers. When seen alive in a calm rock-pool, the familiar 

 form of the coral is hidden by a mantle of emerald-green 

 tentacles, but as the tide falls and the polyps contract, the 

 green colour fades away, exposing the ends of the red tubes 

 of which the skeleton structures are composed. 



The Organ-pipe coral arises from a flat membranous 

 plate, which spreads over the surface of the substance to 

 which it is attached. From this plate of attachment or 



i^— ^ 



Fig. 51. — Tiibipora niitsica. Apiece 

 of a large colony, showing the tubes 

 and the horizontal platforms from which 

 young tubes spring, P. One of the 

 tubes, T., has been dissected to show the 

 tabulae. Nat. size. 



