Sharks The Animal Answer Guide

144 Sharks: The Animal Answer Guide

If the sawfish does use the technique described above for catching school-

ing prey, it is one of the few animals that is minimally bothered by the

confusion created by a large group of prey fishes, which is a primary reason

prey fishes form schools in the first place. The sawfish is freed from the

necessity of singling out an individual fish; it can enter a dense school and

slash back and forth.

Finally among our group of special chasers, we have thresher sharks,

whose tail may account for one-half of the body length. For years, re-

searchers and fishers speculated that threshers slashed at and incapacitated

small fish with their scythelike tails, basically using their tail in much the

same way that a sawfish is supposed to use its snout. Anecdotal evidence

includes many examples of threshers caught by the tail on baited hooks and

trolled lures, something that rarely happens with other sharks.

Video evidence has finally appeared that confirms the use of the tail in

feeding. Researchers working off the California coast towed video cam-

eras ahead of baits and filmed Common Threshers approaching the baits.

Use of the hammer during feeding by a Great Hammerhead Shark. (A) Shark chases ray. (B) Shark strikes down across
the back of ray with the flat underside of its hammer. (C) Ray bounces off the bottom from the force of the blow while
shark brakes with its pectoral fins. (D) Shark delivers a second downward blow across the back of ray. (E) Shark pivots
while holding ray against the bottom and takes a bite from front of left pectoral fin. (F) Injured ray attempts to swim
off, followed by shark. From W. R. Strong, F. F. Snelson, and S. H. Gruber, “Hammerhead Shark predation on stingrays: An observation of prey
handling by Sphyrna mokarran,” Copeia 1990 , 836 – 40 ; used with permission of the American Society of Ichthyologists and Herpetologists

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