CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE MUSEUM OF COMPARATIVE ZOOLOGY AT 



HARVARD COLLEGE, NO. 247. 



ON THE STRENGTH AND THE VOLUME OF THE 

 WATER CURRENTS PRODUCED BY SPONGES^ 



G. H. PARKER 



Ever since Grant discovered the currents produced in water by 

 living sponges, this activity has been a matter of interest to the 

 naturahst. The arrangement of the canals within the body of the 

 sponge, the disposition of the motor elements or choanocytes, and 

 the control of currents by means of sphincters have all received 

 much consideration. Very little attention, however, has been 

 given to the currents themselves, their strength and volume. 



In a paper published in 1910 in the eighth volume of The 

 Journal of Experimental Zoology, I recorded the fact that in 

 Stylotella, a sponge from the coast of North Carolina, the pressure 

 of its currents was equal to that of a column of water from 3.5 

 to 4 mm. in height. This sponge is of small size and generates 

 only a slight disturbance in the surrounding water as compared 

 with what may be seen in the vicinity of large sponges in the 

 tropical and subtropical seas. Here the water often wells up so 

 abundantly from the sponge as to deform the surface of the sea 

 much as a vigorous spring deforms that of a pool into which it 

 issues. Sponges of this description are frequently met with in 

 the waters about the Bermuda Islands, and, during a recent 

 sojourn at the Bermuda Biological Station, I took the opportunity 

 of measuring the currents from some of these organisms. 



The method that I used in making these measurements was the 

 same as that which I had previously employed for Stylotella. A 

 whole sponge or a large portion of one was transported in a tub 

 or bucket to the laboratory and a glass tube of appropriate size 

 was tied securely into one of its oscula. Care was taken to select 

 for this purpose an osculum whose canal system had been unin- 



' Contributions from the Bermuda Biological Station for Research, No. 32. 



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