180 GIANT FISHES 



slowly over the sea-floor. It may be emphasized here that 

 when a Flatfish leaves the bottom it swims on its side, with 

 the eyed or coloured side uppermost. 



The Halibuts are voracious fishes, found at all depths from 

 quite close inshore in the case of the small fish to 200 fathoms 

 or more in the case of large individuals. Their preference is 

 for offshore banks of moderate depth, or for deep and rocky 

 situations. They are often to be found in numbers on grounds 

 frequented by cod — a fish with a similar diet. Their food 

 consists largely of fishes of various kinds, but crabs and shell- 

 fish are also eaten. Dr. Goode has stated that " they often 

 kill their prey by blows of the tail, a fact which is quite novel 

 and interesting ". 



The same author describes how the Halibuts catch fish 

 which " they waylay lying upon the bottom, invisible by means 

 of their flat bodies, coloured to correspond to the general 

 colour of the sand or mud upon which they rest ". As in 

 other Flatfishes, the coloration of the eyed side of a Halibut 

 bears a close resemblance to that of the ground upon which it 

 lies, and furthermore, it has the power of changing its colora- 

 tion in harmony with its surroundings developed to a remark- 

 able degree. A fish lying on a patch of mud will be almost 

 black, but if it should happen to move to a sandy ground, the 

 prevailing hues will at once become pale. It has been proved 

 that in order to change its colours the fish must be able to see 

 the ground on which it lies, and if we look at a Flatfish living 

 in an aquarium, with its eyes standing out from its head and 

 moving round independently in almost every direction, rather 

 like miniature gun-turrets, we can see how this may be 

 accomplished. A fish that has been blinded will remain quite 

 dark even if transferred to a white background. Further, 

 experiments have shown that if a Flatfish be placed with its 

 head on a white ground and its body on a black ground, the 

 whole fish will become pale. 



As is well known, the coloration is due mainly to the 

 presence in the skin of numerous pigment-containing cells known 

 as chromatophores. Each of these has the form of a minute 

 bag with thin and highly elastic walls, supplied with fine 

 muscles, which are in turn associated with delicate nerve- 

 endings. The colour change is brought about roughly in the 



