Chap. 22 



SPONGES — A SIDE LINE OF EVOLUTION 



SCATTERED SPONGE CELLS REORGANIZE 



463 



A. Red sponge 

 Cells reunite when 

 pressed apart. 



3 Scattered cells 

 Ameboid cells: 

 collared cells ttiot 

 will regain collars. 



C. Ameboid cells move about, 

 make contacts witti ottier cells. 



D. Groups of cells ore reformed. 



Fig. 22.9. Regeneration of the redbeard sponge, Microciona prolifera. A, its 

 natural growth; B, cells of the living sponge after it was broken up by being 

 pressed through a fine cloth strainer; C, random movement of an ameboid cell 

 (archeocyte) observed two and a half hours; D, the amebocytes have begun the 

 reorganization which continues until the canals and chambers are reformed and 

 new spicules are produced. (C, courtesy, Galtsoff, Jour. Exper. ZooL, 42:197.) 



Marine Sponges 



Marine sponges are notable for their characteristics and biological and 

 economic importance (Fig. 22.10). 



Uses. The absorbent quality of sponges has long been known. Roman 

 soldiers carried sponges with them to use for drinking cups. The era of bath 

 sponges was followed by one of sponges for automobiles, and both have been 

 displaced by plastic sponges. Needless to say, the sponge industry has been 



