194 



American Fisheries Society 



TABLE I. 



Showing the relative resistance of two Puget Sound 

 commercial shrimps, the coonstripe (Pandalus danae 

 Stimp.) and the deep coonstripe (Pandalus stenolepis 

 Rath), from different depths to a temperature of 24° C. 

 The animals were kept at this temperature in small 

 dishes containing sea water surrounded by a large mass 

 of water heated by an alcohol lamp. 



Marine animals, particularly fishes and Crustacea, 

 take on the color of the background present during de- 

 velopment and those from considerable depth are pale 

 in color and the shrimp have decidedly luminescent eyes. 

 The relation of color to light and background has caused 

 the shrimps from the different levels to be easily dis- 

 tinguished and also leads to the conclusion that they 

 have lived at the level from which they were collected 

 since an early juvenile condition, because it is only in 

 the young that such changes can be brought about. The 

 shrimps from the different levels were placed in the 

 same dishes during the experiments so as to preclude 

 the possibility of the different individuals, having been 

 experimented upon under different conditions. The 

 general results were confirmed by numerous tests at 

 other temperatures. 



It will be noted that the shrimps of each species from 

 deeper water died in a shorter time. Likewise the shrimp 

 which habitually lives at greatest depth dies much 



