Chapter Five 



PORIFERA 



(The Sponges) 



Sponges at one time were regarded as plants. 

 When, at last, their animal nature was discovered, 

 their exact relationship and position in the animal 

 kingdom was not clear. For a while they were 

 thought to be large colonies or masses of unicellular, 

 microscopic animals. Finally, from a study of their 

 life history, it was concluded that they were individ- 

 ual multicellular animals. Although there are a 

 great many microscopic animals made up of a single 

 cell (Protozoa), the sponges are usually regarded as 

 the simplest group of multicellular animals (Meta- 

 zoa). 



The sponge with which everyone is familiar, the 

 commercial Bath Sponge, is really only the dried 

 skeleton of the original living animal. When these 

 large sponges are seen alive in their native environ- 

 ment, such as off the coast of Florida, they can be 

 seen to be covered with a thin gelatinous layer of 

 skin. After the sponges are obtained from their 

 home at the bottom of the sea, they are dried and in 

 this way the fleshy skin is removed. 



The greatest variety of sponges of the east 

 coast of North America is found off Florida, the 

 Bahamas and the West Indies. Visitors to- Tarpon 

 Springs, Florida, or to Nassau, Bahamas, often visit 

 the sponge boats to see the interesting diving equip- 

 ment and the unusual animals found at the bottom 



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