AUTHOR S ABSTRACT OF THIS PAPER ISSUED 

 BY THE BIBLIOGRAPHIC SERVICE, JUNE 1 



THE AMOUNT OF BOTTOM MATERIAL INGESTED BY 

 HOLOTHURIANS (STICHOPUS)i 



W. J. CROZIER 

 Bermuda Biological Station for Research 



TWO CHARTS 



I. It has repeatedly been suggested that animals which obtain 

 their food by the ingestion of sandy or muddy bottom materials 

 harboring minute organisms may exert an important influence 

 upon the local topography of the sea-floor. No attempts seem, 

 however, to have been directed toward estimating the amounts 

 of material which may actually be 'worked over' in this way. 

 Large holothurians, such as Stichopus, Actinopyga, and to a lesser 

 degree species of Holothuria, are found in great profusion upon 

 shallow littoral bottoms among ' coral' reef islands in the warmer 

 seas, and Gardiner, Verrill, Mayer, and other observers agree in 

 attributing to them a particular significance for the disintegra- 

 tion and scattering of calcareous bottom deposits. These rela- 

 tively huge holothurians are very plentiful, they usually contain 

 a considerable amount of sand, and the bottom is in places 

 thickly strewn with their castings; it is very natural to suppose 

 that the feeding activities of these animals may have an effect 

 upon the sea-bottom not unlike that, so carefully described by 

 Darwin, which earthworms produce in the soil. Thus it might 

 be considered that the production of many fine sand particles 

 would be facilitated by mutual grinding in the intestinal tract, 

 and that the intestinal juices might also aid in the solution of 

 calcareous fragments. From this point of view, as well as with 

 the object of securing data for use in a study of digestion in these 

 holothurians, I have endeavored to estimate the amount of 

 bottom material which may be passed through the digestive 



' Contributions from the Bermuda Biological Station for Research. No. 88. 



379 



