7. CHEMICAL COMPOSITION
203
The carbohydrate content of Meganyctiphanes norvegica, Thysanobsa
sp., and Nematoscelis megalops has been determined by Raymont and
Conover (1961). They found 0.04-0.08% wet wt (mean 0-05) in Meganyctiphanes norvegica, 0.09-0.1 1 yo wet wt (mean 0-10) in Thysanoessa
sp., and 0.08-0.17% wet wt (mean 0.13) in Nematoscelis megalops.
Feeding of Meganyctiphanes norvegica and Thysanoessa sp. did not
appear to affect the levels of monosaccharides and glycogen present in
their bodies when compared to the levels found in starved animals.
Raymont and Conover conclude that the normal carbohydrate content
of Meganyctiphanes norvegica and Thysanoessa sp. is probably about
O-lOyo wet wt. Most of their analyses of carbohydrate content of
Nematoscelis megalops were made on animals from the same plankton
haul and so further analyses are required before too much emphasis
can be ascribed to the higher levels of carbohydrate found in this
species. There is no information available on the fluctuations, with
diet, of carbohydrate content of N . megalops.
The calorific values of Meganyctiphanes norvegica and Euphausia
krohnii have been measured in a miniature bomb calorimeter by
Phillipson (1964). He found values of 5.230&0.033 Kcal/ash-free g in
M . norvegica and 5.251&0.131 Kcallash-free g in E . krohnii. Vinogradova (1967) quotes a calorific value, for euphausiids found in the
Seas of Japan and Okhotsk, between 352 and 477 Kcal per 100 g dry
material and a value for E . superba of 400-478Kcal per 1OOg dry
material. Small (1967) assessed the calorific value of three size groups
of E . paciJica ; animals weighing 0.3-1.8 mg dry weight (mean 0.9) had
a value of about 428 Kcal per 100 g dry material, animals weighing
1.9-6.0 mg (mean 4.3) had a value of about 453, and animals weighing
6.1-15.5 mg (mean 8.2) had a value of about 516.
The lipids of euphausiids which have been investigated are really
depot fats. These animals store " fats ", " oil ", " lipids "-these
terms referring to the same material in the present discussion are very
loosely used throughout the literature although Lovern (1964), in his
review of the occurrence of lipids in marine organisms, restricts the
term lipid to selected derivatives of higher fatty acids and includes
some other closely related compounds. The lipids were invariably
extracted and weighed by Fisher prior t o the estimation of vitamin A.
Consequently, much useful information on seasonal fluctuations in the
stores of lipids present in Meganyctiphanes norvegica and Thysanoessa
raschii was obtained. The fat metabolism of euphausiids is not well
known and several reports, in the literature, of the percentage contents
of lipids do not state the time of year a t which the animals were caught.
Sheard (1953) points out that more lipid material is stored in the bodies
203
The carbohydrate content of Meganyctiphanes norvegica, Thysanobsa
sp., and Nematoscelis megalops has been determined by Raymont and
Conover (1961). They found 0.04-0.08% wet wt (mean 0-05) in Meganyctiphanes norvegica, 0.09-0.1 1 yo wet wt (mean 0-10) in Thysanoessa
sp., and 0.08-0.17% wet wt (mean 0.13) in Nematoscelis megalops.
Feeding of Meganyctiphanes norvegica and Thysanoessa sp. did not
appear to affect the levels of monosaccharides and glycogen present in
their bodies when compared to the levels found in starved animals.
Raymont and Conover conclude that the normal carbohydrate content
of Meganyctiphanes norvegica and Thysanoessa sp. is probably about
O-lOyo wet wt. Most of their analyses of carbohydrate content of
Nematoscelis megalops were made on animals from the same plankton
haul and so further analyses are required before too much emphasis
can be ascribed to the higher levels of carbohydrate found in this
species. There is no information available on the fluctuations, with
diet, of carbohydrate content of N . megalops.
The calorific values of Meganyctiphanes norvegica and Euphausia
krohnii have been measured in a miniature bomb calorimeter by
Phillipson (1964). He found values of 5.230&0.033 Kcal/ash-free g in
M . norvegica and 5.251&0.131 Kcallash-free g in E . krohnii. Vinogradova (1967) quotes a calorific value, for euphausiids found in the
Seas of Japan and Okhotsk, between 352 and 477 Kcal per 100 g dry
material and a value for E . superba of 400-478Kcal per 1OOg dry
material. Small (1967) assessed the calorific value of three size groups
of E . paciJica ; animals weighing 0.3-1.8 mg dry weight (mean 0.9) had
a value of about 428 Kcal per 100 g dry material, animals weighing
1.9-6.0 mg (mean 4.3) had a value of about 453, and animals weighing
6.1-15.5 mg (mean 8.2) had a value of about 516.
The lipids of euphausiids which have been investigated are really
depot fats. These animals store " fats ", " oil ", " lipids "-these
terms referring to the same material in the present discussion are very
loosely used throughout the literature although Lovern (1964), in his
review of the occurrence of lipids in marine organisms, restricts the
term lipid to selected derivatives of higher fatty acids and includes
some other closely related compounds. The lipids were invariably
extracted and weighed by Fisher prior t o the estimation of vitamin A.
Consequently, much useful information on seasonal fluctuations in the
stores of lipids present in Meganyctiphanes norvegica and Thysanoessa
raschii was obtained. The fat metabolism of euphausiids is not well
known and several reports, in the literature, of the percentage contents
of lipids do not state the time of year a t which the animals were caught.
Sheard (1953) points out that more lipid material is stored in the bodies