SPONGES AND CORALS 



History, weighs no less than 579^ pounds — over a quarter 

 of a ton. 



These are but few of the fantastic creatures which 

 inhabit the coral reefs, and are the companions of the 

 sponges. 



For a long time sponges were thought to be plants, but 

 we now know them as skeletons — each one the frame- 

 work of a slime-animal. The sponge you hold in your 

 hand may have come from the warm deep waters of the 

 Grecian Archipelago, or it may have grown to maturity 

 in the Red Sea. But the waters of the Mediterranean, 

 the Dodecanese Islands, and the Gulf of Mexico, are 

 the ideal environment for sponges — owing to their free- 

 dom from strong currents, and the favourable tempera- 

 tures. Sponges are so prolific and of such fine quality in 

 the Gulf of Mexico that it is now the world's largest 

 sponge market. 



Sponges are woven of a material that resembles the 

 material spun by silk worms. When alive, the cells on 

 the outside of the skeleton procure food and oxygen 

 for the organism. They do this by using flagella — fine 

 hair-Hke appendages — which whip the water into the 

 canals, driving streams of it through them, so that the 

 food and oxygen can penetrate through the whole 

 system. Thomas Huxley described the sponge as a kind 

 of submarine Venice, "where the people are ranged 

 about the streets and roads in such a manner that each 

 can easily appropriate its food from the water as it 

 passes along". 



As it grows at the bottom of the sea, on the ocean 

 shelves, the living sponge is covered inside and out by a 

 gelatinous substance which absorbs particles of floating 

 matter as they pass through the canals. Those particles 

 which are not nutritive are eventually rejected, passing 

 out into the sea again. The creatures may be perpetuated 

 by gemmation — the formation of new individuals by the 

 protrusion and breaking away of parts of the parent. The 



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