Istiophorid Fishes — WiSNER 
69 
grasping prey. If the spear is of use in feeding, 
it is probably of most value in permitting 
high speeds to be attained by the feeding fish. 
It may be argued that the tunas and por- 
poises are also rapid swimmers yet have ter- 
minally opening mouths. However, they too 
are well streamlined and have relatively nar- 
row snouts that no doubt induce minimal 
drag at high speeds. Indeed, their spearless 
heads may be considered analagous to those 
of spearfish without spears. There is little 
doubt but that the tunas and porpoises rely 
on speed to capture prey. 
SUMMARY AND CONCLUSIONS 
It is concluded that the spearfish es rely 
primarily on speed to overtake and engulf 
their food. This circumstance explains why 
spearless marlins are able to obtain food and 
to exist in competition with their undamaged 
fellows. The widely held belief that these 
fishes, marlins in particular, normally stun 
prey with a blow of the spear has presumably 
stemmed from fishermen watching fish turn 
slightly to grasp the bait between jaws or to 
engulf it, during which action the spear per- 
forms a lateral motion readily interpretable as 
a slash or blow. The several instances of stab- 
bings of prey may well have resulted from 
the high speed of the predator and escape 
attempts of the prey, the spear point inad- 
vertantly striking the prey. There is little to 
indicate that most stabbings are intentional. 
In the face of preponderant evidence that 
most of the prey is not stabbed, one must, 
for the present, accept the probability that 
such spear penetrations are quite accidental. 
Further evidence that these fishes rely on 
speed to overtake prey are the numerous ac- 
counts of the ramming of ship hulls and 
floating objects. It seems logical to assume 
that many such rammings result when spear- 
fishes charge prey lying under these vessels 
and either fail to see the hull or misjudge the 
distance between prey and hull. The depths 
of penetration strongly indicate that the spear- 
fish was not using its spear as a flail to obtain 
food. Such penetrations of objects could have 
resulted only from a straight-forward charge, 
either to seize the prey lying underneath or 
to battle a fancied enemy. 
The restrictions in rapid lateral movement 
imposed by the highly integrated and rein- 
forced vertebral column render it highly im- 
probable that such fishes normally kill or stun 
prey by slashing with their spears, particularly 
when in pursuit of fleeing prey. The rough- 
ened surface of the spear and its relatively 
blunt tip preclude the possibility of stabbing 
the smaller fishes and the squid, which com- 
prise the major food items of the spearfishes. 
In whatever way it is used, the spear pre- 
sumably serves a hydrodynamic function, in- 
creasing the speed of these large fishes. In 
feeding it presumably does more. The form 
of the spear and of the adjacent parts of the 
head seem well fitted to avoid drag, escape 
of prey, and possible injury at high speeds 
when the mouth is opened. A rapid water 
flow is induced past the mouth region, and 
the mouth appears to be so formed as to 
present minimal resistance when closed and 
but slight resistance when opened to seize 
prey. 
REFERENCES 
Anonymous. 1955.2. Pacific Oceanic Fishery 
Investigations. Natl. Canners Assoc., Fishery 
Inform. Bui., 22 April, pp. 83-84. Wash- 
ington. 
Anonymous. 1955 b. Feeding marlin uses 
its head. Internatl. Oceanographic Found., 
Bui. 1(3): 38, 39- 
Bandini, Ralph. 1933. Swordfishing. Calif. 
Fish and Game 19(4): 241-248. 
Berg, Leo S. 1947. Classification of Fishes, Both 
Recent and Fossil.). W. Edwards, Ann Arbor, 
Michigan. 
Farrington, S. Kip, Jr. 1937. Atlantic Game 
Fishing. New York. 298 pp. 
1942. Pacific Game Fishing. New York. 
290 pp. 
