lyo Dwellers of the Sea and Shore 



that capture the minute plants and animals which pass 

 in through the pores with the circulating water. But 

 please understand — it is not the cilia, or hairs, that 

 catch the food; their office is merely to create the cur- 

 rents which keep the water moving, a condition main- 

 tained hy their constant vibration; they both take in 

 their food and eject the waste products of digestion 

 through the circular orifice within the collar. Thus, in 

 fine, the sponge works something like this : Through 

 the innumerable fine pores that cover the outside of the 

 animal, the water is strained of its coarser particles of 

 floating food and the finer material is carried through 

 incurrent canals into ciliated sacs or chambers, the cells 

 of which select and absorb the suitable ingredients; 

 thence the streaming atoms are diverted into the large 

 channels and pass out through craterlike vents called 

 osciila. In proportion to the pores, the oscula are few 

 in number; in fact, it is due to the porous structure of 

 sponges that they have received the scientific name 

 Porifera. 



The sponges are singular in having no natural ene- 

 mies — unless we humans in our commercial exploita- 

 tions of these animals can be included in this category. 

 But even here our attention is confined only to the 

 genus Spong'ui; and we make some effort to compensate 

 for their reduction by artificial propagation. Living 

 sponges are cut into pieces, and these are planted in the 

 most suitable situations favoring their growth. They 

 grow rapidly, attaining a marketable size within a year. 

 The commercial sponges of this hemisphere are all 

 taken from Florida waters, and off the shores of the 

 Bahamas and the West Indies in depths of less than 



