132 Commercial Shark Fishing in the Caribbean Area 



Figure 48 



Family Sphrynidae, Hammerhead Sharks. Sharks with the head 

 much flattened above and below and very widely expanded sideways 

 in the form of a "hammer" or "bonnet" and with the eyes at its outer 

 edges. Otherwise the characters are in general like the family 

 Eulamidae. 



Genus Sphyrna. Characters as in family and with nostrils much 

 closer to the eyes than to the mid-line of snout. 



Figure 48. Sphyrna tiburo, Bonnet Shark, Shovel-head. 



Description: Trunk moderately flattened sideways; head 

 "shovel" — not "hammer" — shaped, the front contour being an un- 

 interrupted curve from eye to eye without definite depressions 

 opposite nostrils ; the distance from nostril to eye is slightly greater 

 than diameter of eye; the corners of mouth are slightly in front 

 of the outer rear corners of the head or "shovel"; diameter of eye 

 about 1/4 to 1/5 as long as length of head in front of mouth; 

 length of first gill opening about 1-1/2 times diameter of eye; fifth 

 gill opening over origin of pectoral; teeth are in 12 to 14 rows on 

 each side of upper jaw and in 12 rows on each side of lower, with 

 one very small tooth usually in the center of both upper and lower 

 jaw; in the upper jaw the first tooth from center is erect, but the 

 subsequent teeth become increasingly oblique; in the lower jaw 

 the first 1 to 3 teeth are erect, the next 4 or 5 are slightly oblique 

 and the few near corners of mouth are low, oval and have no 

 cutting edge; free rear margin of second dorsal about 1/3 as long 

 as vertical height of fin and not longer than its front margin ; 

 pelvics with weakly convex front margin and weakly concave rear 

 margin ; and rear margin weakly concave. 



Color: Gray or grayish brown above and paler shade of same 

 hue below. Some fish have a few small round dark spots on the 

 sides, but there are no conspicuous fin markings. 



Size: Seldom exceeds 5 feet, with 6 feet about the maximum. 



Habits: Found chiefly in shallow water and close inshore (less 

 than 5 fathoms), often in bays and estuaries. It feeds largely 

 on crabs and shrimps, but also takes mollusks, octopuses, small fish 

 and almost any animal it can capture. 



Range: Tropical and warm temperate belt of the Atlantic Ocean 

 from southern Brazil to North Carolina and, as a stray, to southern 

 New England and Massachusetts Bay; apparently found in tropical 

 West Africa and also on the Pacific coasts of America from south- 

 ern California to Ecuador. 



