OF SOME COMMON MARINE ANIMALS 



259 



recently, samples of zoo-plankton [Calanus) and pbyto-plankton (Diatoms) 

 which I had collected in the Irish Sea for the purpose and transferred in the 

 living condition into absolute alcohol. His results are as follows * : — 





t, , .■ , Carbohydrates Fats 

 I'roteuts. ,, j. i v- J / , • .x 

 1 (by difference), (-(-pigment). 



Ash. 



Phyto-plankton 1 

 ( ChcBtoceros) ... \ 



Zoo-plankton . . ( 

 (Calanus)' . . . . \ 



31-6 

 031 



29'7 

 18-2 



24-2 

 17-6 



14-5 

 111 



And, no doubt, the animals of the benthos — the common invertebrates of our 

 shores — will show similar differences in analysis t- It is obvious that some 

 contain more solid flesh, others more water, in their tissues, others more 

 calcareous matter in the exoskeleton, and that therefore weight for weight 

 we may be sure that some are more nutritious than the others ; and this is 

 probably at least one cause of that preference we see in some of our bottom- 

 feeding fish for certain kinds of food, such as Polychset worms, in which 

 there is relatively little waste, and thin-shelled Lamellibranch Molluscs, such 

 as young mussels, which have a highly nutrient body in a comparatively thin 

 and brittle shell. 



I am aware that I am presenting a somewhat incomplete investigation, but 

 my object is to direct attention to what seems an obvious and useful exten- 

 sion of faunistic work, for the purpose of obtaining some approximation to a 

 quantitative estimate of the more important animals of our shores and 

 shallow water and their relative values as either the immediate or the 

 ultimate food of marketable fishes. 



* These figures differ somewhat from those given by Brandt, and this may possibly be 

 due to differences between these types of plankton at Kiel and in the Irish Sea — which raises 

 the interesting question whether the same organism nuiy have different nutritive values 

 under different hydrographie conditions. 



t Moore and others have made analyses of the protein, fat, &C-, in the soft parts of 

 Sponge, Ascidian, Apli/sia, Fusus, Echinus, and Cancer at Port Erin, and find considerable 

 differences — the protein ranging for example from 8 to .",1 per cent and the fat from 

 2 to 14 per cent (see Bio-Chemical Journ. vi. p. 255;. 



