254 T'he Life Story of the Fish 



hatched. These infinitesimal animals, like any other young 

 fish, have a yolk-sac, which it takes them about ten days to 

 absorb, and they develop an air-bladder. They swim around, 

 like any other young fish, with one eye on each side of the 

 head, but at an early age they stray from the conventional 

 path. They begin to grow flat, but instead of being flattened 

 from top to bottom like the skate they are flattened from 

 side to side. They begin to lean over more and more to one 

 side or the other, and at the same time the eye on the side to 

 which they are leaning begins a migration. It may travel 

 across over the top of the head, or it may travel through 

 the head, but it eventually lands alongside the other eye — 

 unless, as sometimes happens, it gets lost inside the head and 

 never appears again. In general, all the fish of the same 

 species use the same side to see out of. Most of the flatfishes 

 we eat in this country are "dextral" — ^they have the eyes on 

 the right — while many of the tropical flatfishes are "sin- 

 istral" j but there are some species in which both right- and 

 left-sided individuals occur. In any case, it is only after the 

 migration of the eye that the fish settles on the bottom. The 

 under side then becomes colorless, and the air-bladder dis- 

 appears. The end result is a fish which lives on its eyeless, 

 colorless right or left side, and presents to the world its left 

 or right side which contains both eyes and which is colored 

 to match its background. And the surprising point is that 

 the whole transformation takes place within the first six to 

 twelve weeks of the fish's career, and that in most of the 

 species the little animals are not yet an inch long when the 

 change is completed and they give up wandering to settle 

 on the bottom for the rest of their lives. However, they do 

 not "refuse to get up again," as our journalist suggests, for 

 their food does not "drift down" into their mouths. They 

 are carnivorous, and have to spend a certain amount of time 

 pursuing their prey. 



