A harpactacoid copepod, Scottolana canadensis , was found less capable 

 of using detritus and associated microorganisms, but could obtain some 

 energy from that source. (A. A.) 



Keywords: food chain, detritus, estuaries, productivity, Maryland 



III-E-17 



Fox, D.L. 1950. Comparative metabolism of organic detritus by inshore 

 animals. Ecology 31 : 100-1 08. 



This report considers the sources, character, and disposition of 

 marine detrital organic matter and the subsequent metabolism of detritus 

 by inshore animals. The author divides the various species of detritus 

 feeders into three main groups: animals that filter detritus through 

 use of cilia or net structures; animals that graze upon the ocean floor 

 utilizing tentacles or a muscular pharynx (sucking); and animals that 

 feed by scraping adherent material from rocks, shells, pilings and 

 other submerged surfaces. Several findings are reported. 



The sizes of populations that will be supported in a marine inshore 

 area are dependent upon the quantities of organic detritus that may 

 serve as food, either directly or by contributing to the total carbon 

 budget. 



Great numbers of marine invertebrates feed primarily upon organic 

 detritus. They obtain it by (1) filtering such colloidal or other 

 fine particulate material from the water, (2) swallowing whole mud, 

 sand and other inert material to which the organic matter is adsorbed, 

 or (3) scraping it from extensive inmersed surfaces. 



Biochromes, such as red, orange or yellow carotenoids or greenish 

 breakdown products of chlorophyll, provide valuable means of studying 

 the comparative biochemistry of nutrition and assimilation, especially 

 as derived from suspended or precipitated detrital materials. 



While xanthophyll ic carotenoids are more common than carotenes in 

 fresh, suspended plankton and detritus and in numerous detritus 

 eaters, carotenes are the predominating carotenoids of buried marine 

 muds, and of a few detritophagous animals. 



Comparisons are drawn between two typical marine detritus feeders: 

 (a) mussels, which filter vast quantities of water annually, removing 

 therefrom the finely suspended organic matter from which some of the 

 xanthophylls are assimilated and the carotenes quantitatively rejected, 

 and Cb) the beach-annelid, Thoracophel ia , colonies of which cycle tons 

 of sand annually through the alimentary tract, gaining nutrition from 

 the adsorbed film of colloidal organic matter, from which B-carotene 

 is selectively assimilated, while xanthophylls are rejected and largely 

 destroyed. 



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