PLANKTON 25 



attested to by Dr. S. P. Chu, who wrote to Clarke in 1946 from Yunnan 

 that Chinese peasants had long used marine plankton as food. 159 In the 

 same year, too, Sir Hubert Wilkins wrote Bajkov that he had eaten plank- 

 ton in the Antarctic with no ill effects. 



In 1945, Knowlton and Irving, 170 of the Aero-Medical Laboratory, 

 studied the effect of eating plankton upon the water requirements of men 

 on life rafts. Their investigation was basically a physiologic analysis of the 

 nutrients of copepods caught in Buzzard's Bay (Massachusetts) by Bajkov. 

 On the basis of determinations made by Dr. A. Butler, the chloride con- 

 centration of the plankton was calculated as about 0.57 per cent, as com- 

 pared with 1.9 per cent in sea water. The protein content was 51 per cent, 

 while the fat was estimated to vary from 10 to 30 per cent. If 800 ml. 

 drinking water are available daily (from solar still, desalination kit, and 

 captured rain water), they concluded that over 300 calories could be 

 derived from plankton before the limits of salt excretion were reached. 

 With this amount of planktonic protein metabolized, the urinary nitrogen 

 produced would be about 12.4 gm., also a serious consideration when 

 water intake is limited. 



Robinson and Bajkov mentioned in their 1947 report 159 that about 

 twenty of their human subjects ate 50 to 100 gm. plankton at one meal 

 without ill effect, and that one individual even consumed a full pound 

 without harm. The plankton in these experiments came from Atlantic, 

 Pacific, and Gulf of Mexico waters. In most instances, the plankton was 

 considered quite palatable. The raw plankton tasted like raw oysters, while 

 the cooked material resembled cooked shrimp. Variations in the smell of 

 raw plankton were produced by admixtures of certain species of diatoms 



and dinoflagellates. 



In the same report, Robinson and Bajkov gave the results of feeding 

 plankton to rats. Knowing that Atlantic plankton could be digested and 

 assimilated by rats (studies at Woods Hole Marine Laboratory, 1945), 

 they successfully repeated the procedure with fresh water plankton from 

 an Ohio lake, and also proved that it had a specific growth-producing 

 value. Similar results were then obtained with Pacific plankton. Com- 

 parative analyses of several types of plankton were listed (Table II). 



It is apparent that the composition of plankton varies with geography, 

 climate, and the predominant species of organisms. Water comprises 75 to 

 85 per cent of marine copepod plankton. On a dry weight basis, 45 to 60 

 per cent may be protein; 4 to 31 per cent, fat; 18 to 23 per cent, car- 

 bohydrate; and 0.5 to 20 per cent, ash. Chitin is usually present in less 



