THE SPONGES OF THE WEST-CENTRAL PACIFIC 267 



Sponges require the various ions which are normally present in sea 

 water, perhaps thrive in ratio to the abundance of some, such as phosphate 

 and silica. 



Jorgensen, 1944 de Laubenfels, 1932 



Galtsoff, 1925 de Laubenfels, 1950 



Sponges thrive at all temperatures normally present, but each species 



has narrow limits and dies if temperatures become colder or warmer than 



those which are normal to its selected environment. 



Jewell, 1935 Orton, 1920 



Arndt, 1937 de Laubenfels, 1932 



McDougall, 1943 



Sponges have certain limits of bathymetric tolerance for each species, 



probably correlated with both temperature and oxygen, although one species 



or another is adapted to practically every oceanic depth. 



Arndt, 1943 Burton, 1928 



Bassindale, 1943 Chumley, 1918 



Minchin, 1900 Stephenson & Stephenson, 1948 



de Laubenfels, 1936 (paleo) 



Sponges frequently contain symbionts ; individual species may well de- 

 pend upon such symbionts for nourishment. The requirements for light are 

 very significant for such species, but utterly insignificant for other sponges. 



van Tright, 1919 Dendy, 1926 



van Weel, 1949 Weber & Weber, 1890 



de Laubenfels, 1932, 1947 Pearse, 1932 



Sponges react upon neighboring sponges, often adversely. This may have 

 survival value in obtaining suitable space from other (competing) sponges, 

 de Laubenfels, 1928, 1932 

 Sponges may be displaced by other animals, but this appears rare. Data 

 in the present article may be the first of this sort. 



Sponges are attacked by a few predators, such as angel fish and sea 

 turtles. 



de Laubenfels, 1932, 1947, 1950 



Sponges suffer from numerous internal parasites and even from disease 

 epidemics. 



Dosse, 1939 de Laubenfels, 1947, 1950 



Galtsoff, 1940 



Sponges attach to and damage or smother other animals. 

 Annandale, 1914, 1915 Old, 1941 



Churchill, 1920 Volz, 1939 



The first item for ecological consideration is the amazing paucity of 

 sponges in the Marianas. Only guesses can here be made as to the reasons. 

 The surmise that seems most plausible to me is that the great hurricanes or 

 typhoons which periodically ravage this archipelago may be responsible for 

 the lack of sponges. 



