138 Commercial Shark Fishing in the Caribbean Area 



Figure 51 



Family Sphrynidae, Hammerhead Sharks. 



Figure 51. Sphyrna tudes, Great Hammerhead. 



Description: Trunk moderately flattened from side to side. The 

 front contour of head with a depression opposite each nostril and a 

 shallow but noticeable indentation at the mid-line of head ; the 

 distance from nostril to eye is about equal to diameter of eye ; in 

 adults the corners of mouth are slightly behind the rear margin 

 of the head or "hammer", but in newborn and very young speci- 

 mens the rear corner of mouth is slightly in front; diameter of eye 

 about 1/3 as long as head in front of mouth in young fish, but 

 increasing so little in size in large ones that it may be only about 

 1/5 as long; length of first gill opening about 1-1/3 times diameter 

 of eye in young, but 2 to 3-1/3 times in medium sized specimens 

 and as much as 4 times the eye in large fish (around 10 feet long) ; 

 4th gill opening over origin of pectoral: there are 17 teeth on each 

 side of the upper jaw and 16 or 17 on the lower, with 2 or 3 very 

 small upper and 1 to 3 lower teeth in the center of jaw; the teeth 

 are triangular, the first being erect but the remainder becoming 

 increasingly oblique toward corners of mouth ; the edges of the 

 teeth are serrate from tip to base excepting the 1 or 2 near corner of 

 mouth — none of our other Hammerhead Sharks have serrated 

 teeth ; free rear margin of second dorsal is about 3/4 as long as 

 the front margin of the fin. and only about as long as its vertical 

 height; pelvics with front margin more strongly convex and rear 

 margins more deeply concave than in any other Atlantic members 

 of this genus. 



Color: Small specimens are brownish gray above and a paler 

 shade of the same tint below with the dorsal fins, caudal and 

 upper surfaces of the pectorals dusky toward the tips. Large ones 

 are reputed to be dark olive above and pale olive below without 

 conspicuous fin markings. 



Size: Probably about 28 inches long when born. The largest 

 of the hammerheads apparently mature at about 10 feet and com- 

 monly reach 13 to 14 feet with 15 feet reported. 



Habits: Nothing is known of its habits to set it apart from its 

 close relatives. 



Range: Tropical and subtropical Atlantic but no details of its 

 distribution are known. It is also believed to occur in the Pacific. 



