FISHERY BLLLETIN: VOL, 69, NO- I 



is nitrogen, 6.5 "^r of ciiitin is nitrogen, and 7 '/c 

 of the dry body is chitin: 0.16 ("protein") + 

 (0.065) (0.07) = 0.115. From this relation- 

 ship, the "protein" content of the whole dry 

 body was estimated to be 69 %, which is sim- 

 ilar to the value to 71 % protein estimated di- 

 rectly by Raymont et al. (1964) for Neomysis 

 integer. According to the estimates of Raymont 

 et al. (1968) , the percent nitrogen in proteins of 

 Mysidae may be lower than the value of 16 % 

 commonly assumed for animal tissues. They 

 found 13.3 9r N in the body protein of Neomysis 

 integer, and estimated that about 17 ^/c of what 

 we would have designated as "protein" nitrogen 

 was actually free amino acid nitrogen. They 

 suggest that the amino acids may function in 

 osmoregulation for Neomysis integer, which is 

 a euryhaline-brackish water species. We know 

 nothing directly about this for Metamysidopsis. 

 Our species lives in a constant oceanic salinity, 

 and we estimated the ash content to be higher 

 than that of N. integer. Therefore, a high con- 

 centration of free amino acids may not be ne- 

 cessary for osmoregulation in our species. What- 

 ever the ratio of protein/free amino acids may 

 be in Metamysidopsis , our energy calculations 

 should not be affected materially. 



The lipid content of the mysid bodies was esti- 

 mated by placing samples of dried, crushed 

 bodies successively for 1 hr in each of two 10-ml 

 portions of ethyl alcohol and two 10-ml washes 

 of petroleum ether. The lipid content was esti- 

 mated as the difference in dry weight before 

 and after extraction. Two dry samples of mixed 

 animals, weighing 62.9 mg and 13.4 mg, gave 

 values of 9 % and 11 % lipid respectively. A 

 third sample, containing 24.1 mg of brooding 

 females that had full complements of young in 

 their brood pouches, gave a value of 19 Cr lipid. 

 Linford (1965) found that large females of 

 Neomysis integer carrying young had higher 

 lipid contents than males. From our knowledge 

 of the number of young per female and the esti- 

 mated percent lipid in the young, we calculate 

 that i/i. to 1/2 of the 19 ^r lipid value could be 

 contributed by the brood pouch young. There- 

 fore, we have excluded the 19 ^r value from our 

 estimate, and we have used 10 '/c as the estimate 

 of average lipid content of the dry bodies. This 



is slightly less than the value of 13 7r estimated 

 for Neomysis integer by Raymont et al. (1964), 

 but within the range of means for three species 

 estimated from a large number of determina- 

 tions by Linford (1965): Mesopodopsis slavveri 

 — 9.0 % ; Neomysis integer- — 10.1 S^ ; Praimus 

 neglectus — • 9.3 %. 



The carbohydrate content of the mysids was 

 estimated as the amount of macromolecular 

 material remaining after the average estimates 

 for ash, protein, chitin, and fat are subtracted 

 from the dry weight. This remainder is 1.5 %. 

 Apparently the carbohydrate fraction is low in 

 all pelagic Crustacea. Raymont and Conover 

 (1961) found that 1 '? of the dry weight of 

 Neomysis aniericana was glucose; Raymont and 

 Krishnaswamy (1960) found 1.3 ^r carbohy- 

 drate in dry Neomysis integer; and Raymont 

 et al. (1964) found 2.4 9( carbohydrate in dry 

 Neomysis integer. 



We did no detailed analyses of the composition 

 of molts, but we assume that the molt is com- 

 posed of structural materials rather than energy 

 storage materials. Since we consider that carbo- 

 hydrates and lipids are virtually absent, we 

 entered zero values for them in Table 3. The 

 "protein"/chitin relationship was determined in- 

 directly. First, we estimated the smiount of 

 carbon in the average protein of the mysids from 

 the relationship: 



(■■f C as protein) = C/c C in body) 



— (% C as chitin) 



— (% C as lipid) 



— (% C as carbo- 



hydrate) . 



The percent carbon in the organic fraction of 

 the body is 42 ""f , the chitin fraction is taken 

 as 8 '( , the chitin is assumed to be 50 % carbon 

 (Curl, 1962a), the lipid content of the organic 

 fraction is 11 ""r , the lipid is assumed to be 77 ^c 

 carbon (Lasker and Theilacker, 1962), the car- 

 bohydrate fraction is about 2 % . and the carbo- 

 hydrate is assumed to be 40 % carbon (Curl, 

 1062a). Therefore, the percent carbon in the 



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