SHARKS 47 



There are about live species of Hammer-heads, which exhibit 

 a complete gradation in the shape of the head from that of a 

 kidney in the Shovel-head or Bonnet Shark (5. tiburo) to 

 that of a hammer in the true Hammer-head Shark (5. 

 zygana) ; that of the species S. hides is roughly intermediate. 

 The Hammer-head is a rare visitor to the British Isles. 



These Sharks are often found in deep water, but may also 

 be seen at the surface, with the dorsal and caudal fins projecting 

 from the sea. The curious shape of the head is unique among 

 fishes, and it is difficult to see what use the lateral outgrowths 

 can be to their possessor. It has been suggested that they 

 allow it to manoeuvre and turn with great speed, but, in the 

 absence of direct evidence, this must be looked upon as " a 

 shot in the dark " ! Some idea of the extent of the lobes in 

 the true Hammer-head may be gained from the fact that in a 

 large Shark the width of the " hammer ", measured from eye 

 to eye, may be as much as 3 feet. 



The Hammer-heads live mainly upon other fishes, although 

 squids, crabs, and even barnacles are included in their diet. 

 One individual, more than 13^ feet long, which was caught at 

 Ilfracombe, Devon, in 1865, was found to contain 2 thornback 

 rays and a bass. Dr. Gudger mentions a specimen of I2| 

 feet, harpooned at Beaufort.. North Carolina, as it was chasing 

 some sting rays over sand flats, which had been feeding almost 

 exclusively upon these fearsome creatures. In addition to the 

 semi-digested remains of the rays in its stomach, there were no 

 less than 50 " stings " embedded in various parts of its 

 anatomy ; some were in the neck region and in the back, 

 but the great majority had been driven into the mouth and 

 gullet. Some of the " stings " had been but recently implanted, 

 but others were older and had become embedded in cysts. 



The larger species of Hammer-heads have the reputation of 

 being dangerous to man, but authentic records of attacks are 

 difficult to trace. Indeed, the reputation seems to rest 

 mainly upon the find of the remains of a man, together with 

 parts of his clothing, in a specimen captured in America in 

 1805. 



The Hammer-heads are viviparous, and 37 embryos have 

 been taken from a female 11 feet in length, while another 

 captured in Carmarthen Bay had 31 young. 



