I08 GIANT FISHES 



scales. The mouth is small and toothless, and can be pro- 

 truded by a curious mechanism, the maxillary bones being 

 pulled away from the head by the movement of the lower 

 jaw. There is a single long dorsal fin, with a high lobe at 

 its front end, and a long, low anal fin ; both dorsal and anal 

 fins can be folded back into deep grooves. The pectoral fins 

 are long and sickle-shaped, placed high up on the sides, and 

 their bases are set horizontally on the body. Each pelvic 

 fin is supported by from 15 to 17 rays, and is placed just 

 behind the pectoral. The caudal fin is moderately forked, 

 and is set at the end of a short, slender peduncle ; there is a 

 pit above and below at the root of the fin. The lateral line 

 is much arched in front. There is a large air-bladder, but 

 this is not connected with the gullet. The coloration of the 

 back varies from steel blue to bottle-green, the sides are 

 bluish or greenish, with brilliant reflections of purple and gold, 

 and the lower parts are rose red ; the whole of the body is 

 covered with round silvery spots. The jaws and the fins are 

 bright scarlet. 



The Opah grows to a length of at least 6 feet and a weight 

 of 500 or 600 lb. 



The single known species (L. luna) is widely distributed 

 in the warmer parts of the Atlantic and Pacific. It is rare 

 in the Mediterranean, but is "a not infrequent visitor to the 

 coasts of the British Isles during the warmer months. 



Fossil remains, believed to be those of a fish very like the 

 Opah, have been found in California in rocks of Miocene age. 



This fish must be regarded as comparatively rare, and very 

 little is known of its manner of life. It is apparently solitary 

 in its habits, and is mainly an inhabitant of warm water, but 

 during the summer months in the Atlantic it wanders as far 

 north as Newfoundland, Iceland and Finland. It probably 

 spends a good deal of its time fairly close to the surface, but 

 there is no doubt that at times it descends into deeper water. 

 At Madeira the Opah is taken on lines baited with scad or 

 mackerel at depths varying from 50 to 100 fathoms, and the 

 late Professor Jordan notes that the " long liners " often 

 capture this fish when working west of the Shetlands. From 

 its general build it may be confidently inferred that the Opah 

 is a slow swimmer. 



