68 
There are further indications of the speed 
and power of marlin, and possibly of their 
pugnacity. Morrow (1951) reported having 
seen on a beach in British East Africa a bale of 
crude rubber that held the broken spear of a 
black marlin imbedded 8 or 10 inches into 
rubber so tough a man could not drive a spike 
into it with a heavy hammer. Smith (1956) 
reported on floating rubber bales from the 
African coast. As many as four spears have 
been found in one bale. Another bale con- 
tained 24 inches of the spear of a large black 
marlin embedded to a depth of 13 inches. 
In one bale was found the sword of a broad- 
bill swordfish, indicating that it also charges 
floating objects. 
The reasons for these attacks are not com- 
pletely understood. Some may be the result 
of sheer pugnacity. However, it has long 
been known that fish often lie beneath float- 
ing logs, debris, ship hulls or any fairly large, 
slowly moving object at or near the surface. 
The tuna live-bait fishermen make a practice 
of fishing, often with considerable success, 
close to such objects, including the large 
whale shark, Rhineodon typus Smith. The ram- 
ming of ship hulls may well be the result of 
excess speed and a lack of maneuverability of 
the attacker as it charges to engulf fish lying 
under such shelter. 
Gudger {op. c/t.) supported this view with 
an observation by F. D. Bennett (Narrative 
of a Whaling Voyage Round the Globe, 1833 
to 1836, London, 1840). Bennett tells of alba- 
core [jit'], clustering in a dense shoal under 
the ship, that "swam with an appearance of 
trepidation and watchfullness. The cause of 
this unusual commotion was visible in a 
swordfish, lurking astern, awaiting a favour- 
able opportunity to rush upon his prey when 
they should be unconscious of danger or 
away from the protection of the ship. . . . and 
in the course of the day we observed him 
make several dashes amongst the shoal with 
a velocity which produced a loud rushing 
sound in the sea. ... It is probable, as a 
precaution against the attacks of this mon- 
PACIFIC SCIENCE, Vol. XII, January, 1958 
i 
ster, that albacore, and some other tropical 
shoal fish, attach themselves to ships, . . . , the 
close vicinity of a large body being sufficient [ 
to deter the swordfish from making his usual \ 
impetuous thrusts amidst the shoal; the which, 
when rashly attempted, have given rise to the 
appearance of the broken rostra of these fish 
impacted in the planks of ships, ... as is not 
unfrequently noticed.” Although the name 
"swordfish” is used it may also have been a 
member of the round-speared Istiophoridae, 
as all were termed swordfish until recent years. 
Certainly no flailing at prey could have re- 
sulted in such penetrations of hulls as re- 
corded. The angle of incidence of spear and 
hull would either have deflected the spear or 
have caused only slight penetration. Also, if 
the spearfish had concentrated on a side-to- 
side motion, the greater portion of the total 
energy would have been expended in this 
action. The forward speed would have been 
correspondingly reduced, so as to lessen the 
depth of penetration, regardless of the angle 
of incidence. Only a straight-forward charge 
resulting from pugnacity or an attempt to 
capture prey could result in such penetrations. 
The biological significance of the spear 
may well be an adaptation for the great speed 
and power of these large fish, as well as a 
weapon of defense or attack. I am indebted 
to John D. Isaacs and Carl L. Hubbs for the 
following suggestions. A terminally opening 
mouth would create enormous drag and 
would push in front a mass of water at a 
similar speed, so that a spurt of the intended 
prey would lead it to safety. If the mouth were 
terminal the common mode of ingestion by 
suction due to a sudden spreading of the gill 
covers as the mouth is opened would prob- 
ably be difficult and perhaps dangerous at 
extreme speeds. On the other hand the pro- 
jecting and tapered spear would scarcely im- 
pede the flow of water past the narrowly 
triangular mouth on the lower surface of the 
base of the beak. A sudden snapping of the 
sharply pointed inferior mandible would in- 
duce minimal drag and would be effective in 
