FISHES OF THE PACIFIC COAST 



perature of the water. Most fishes are extremely 

 sensitive to any change of heat or cold. When, 

 as is sometimes the case, the temperature of the 

 water changes abruptly at a given point, the char- 

 acter of the fishes will be found to change with 

 equal abruptness. A very little cold is often suf- 

 ficient to benumb and paralyze a fish of the tropics. 

 I have seen, in the Florida Keys, where the water 

 suffers a slight chill which brings it down perhaps 

 to 80 degrees, the cutlass fish, ordinarily very active, 

 lying stupid and inert on the surface of the water. 

 On the other hand, the fishes of cold regions can 

 not endure any degree of heat to which they are 

 not accustomed; and doubtless the fishes in the 

 depths would be suffocated by the temperature of 

 the surface water, even if their lives were not de- 

 stroyed by the reduction of pressure. 



Another element almost equal in importance is 

 that of depth. The great majority of the marine 

 fishes that we know well, or that we recognize as 

 food fishes, are shore species, inhabiting depths 

 of from one to fifteen fathoms. The great variety 

 of oceanic life is found within this range through 

 which the light and heat of the sun readily pene- 

 trate. As we go lower we find that the shore fauna 

 disappears. The greenish-colored shore fishes give 

 place at fifty to one hundred fathoms to other spe- 

 cies, the prevailing color of which is red. The 

 green or gray colors match the colors of the sand 

 and kelp; the red ones harmonize with the red sea 

 mosses, among which the red fishes live. In still 

 greater depths, where light and heat have dis- 

 appeared, the prevailing hues are violet or black, 

 the color of darkness. 



Of less importance, but still a determining qual- 

 ity for very many fishes, is the character of the 

 food to be obtained. Each species thrives best 

 where those creatures on which it naturally feeds 

 are most abundant. The herbivorous fishes live 

 among the tide pools where they can feed upon 

 the small sea weeds, the crab-eating fishes live 

 among the rocks, and those which feed upon her- 

 rings and silversides flourish best in the open sea. 



The character of the bottom is also of impor- 

 tance. Most of the flounders, for instance, live 

 on a bottom of sand. The so-called rock-cod 

 abound about sunken rocks and banks; while other 

 species are found onlv where the bottom is soft 

 and muddy. The differences between the fishes 

 commonly found at Monterey and at Santa Cruz 

 indicate clearly the differences in the nature of the 

 bottom at these two points on the same bay. 



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