FISHES OF THE GULF OF MAINE 41 



Habits and food. — So rare (and fortunately so) is this shark even in the tropics 

 that practically nothing is known of its habits. It feeds on large fish, on sea 

 turtles, and perhaps on porpoises. Off the California coast sea lions also fall 

 prey to it — vide Jordan and Evermann's account of a young sea lion of 100 pounds 

 weight in the stomach of a 30-foot white shark. As to its breeding habits nothing 

 is known, though presumably it is viviparous like its close relatives. 



/-\ 



Fig. 15. — Basking shark (Cctorhinus maiimux) 



14. Basking shark (Cetorhinus maximus Gunner) 

 Bone shark 



Jordan and Evermann, 1896-1900, p. 51. 

 Garman, 1913, p. 39. 



Description. — The basking shark resembles the other mackerel sharks in its 

 lunate tail, which is much broader than long and with the lower lobe but little 

 shorter than the upper; in the presence of a strong "fore and aft" keel on either 

 side of the root of the tail; in the fact that the second dorsal fin is very much 

 smaller than the first; and in its form, tapering in both directions to snout and 

 tail. However, it is set apart from all other sharks by the enormously long gill 

 slits, which extend nearly right around the neck, and — even more significant — 

 that alone of all its tribe, except its relative the whale shark (Rhinodon), it has 

 rakers on its gill arches, suggesting (though not corresponding to) those of herring, 

 menhaden, etc., among bony fishes. It was the fancied resemblance of these 

 rakers to the whalebone of the whalebone whales that suggested the vernacular 

 name "bone shark" to the whalemen of olden times. 



Corresponding to its feeding habits, the mouth of the basking shark is very 

 large, but its teeth are very small though numerous. I need only note further that 

 the triangular first dorsal fin stands midway between pectorals and ventrals, and 

 though the back fin is little longer in proportion than that of the other mackerel 

 sharks it rises high in the air when the fish lies awash on the surface, as is its habit — 

 a valuable field mark (p. 39). The nose of large specimens is of ordinary "shark" 

 outline — short, conical, bluntly pointed. In young fish, however, up to 12 or 13 

 feet in length, it is curiously contracted in front of the mouth into a semicylindrical 

 snout pointed at the tip. 



