MASTERS OF THE WATER-BONY FISHES 295 



color photograph shows this adaptive coloration to a remarkable degree in one 

 of the small tropical species.) It is even possible for these fishes to assume checker- 

 board or polka dot patterns when placed on such a background. 



Flatfishes do not rest flat against the bottom as might be supposed, even though 

 they sometimes partly bury themselves. They support themselves slightly off 

 the bottom on their decurved dorsal and anal fins. This is done to allow water 

 to pass more easily out of the gill opening on the blind side and also to allow 

 quick getaway after prey (Orcutt, 1950). These fins may also be used for crawl- 

 ing either forward or backward slowly on the bottom by use of wavelike manipu- 

 lations of the fin rays. In swimming in open water, the pectoral and tail fins are 

 used. Flatfishes prefer soft bottoms such as sand or mud or fine gravels. 



These are all highly carnivorous fishes. Some of them have heavy pharvngeal 

 teeth with which they can crush hard-shelled molluscs and crustaceans. 



It is not clear what the relationships of flatfishes are. They have no fin spines 

 and might have been derived from primitive berycoid stock. They are found 

 in all seas, but they predominate in temperate zones. There are many species 

 that are difficult to tell apart. 



FLOUNDERS: Family Plcuronectidae 



The eyes are large and well separated and the mouth is large and toothed in 

 these fishes. The family may be divided into three distinct parts— the halibuts, 

 the flounders, and the turbots. In the first two, the ventral fins are symmetrical, 

 while the turbots have dissimilar ventral fins. The halibuts have large sym- 

 metrical mouths and are the largest members of the family as well as the most 

 primitive. They may be either sinestral or dextral. The flounders have asvmmet- 

 rical mouths and are mostly dextral fishes. The turbots, as well as having asvm- 

 metrical ventral fins and mouths, are usually sinestral, \'ery round in outline, and 

 small in size. 



The common names of these fishes are much confused. On our Atlantic Coast, 

 "sole" refers to a member of the flounder group. The following are examples from 

 each of the major groups— halibuts, flounders, and turbots. 



HALIBUTS 



PACIFIC halibut: Hippoglossus stenolefis 



Size: Reaches 8 feet. 



Weight: Reaches 700 pounds. Rare over 400 pounds. 

 Distrihition: Bering Sea and Alaska south to California. 



Identification: Dextral. This fish is usually a plain brownish to gravish color. 

 Halibuts are not as deep-bodied as most flatfish. 



Atlantic halihitt. 



