Feeding Behavior of Sharks— HOBSON 
173 
though a black dp often approached rapidly in 
response to splashing at the surface, it then gen- 
erally reversed direction and retreated just as 
rapidly if the investigation of the splashing 
brought it into an encounter with a human. In 
the same situation, the grey ordinarily reacted 
to the encounter with a human by continuing 
the approach to approximately 5 yd from the 
human, at which point it would veer aside and 
circle with an apparent cautious interest. If no 
further stimuli were introduced, the grey moved 
on. 
Black tips and greys showed a marked increase 
in excitement when feeding in numbers. This 
phenomenon, generally referred to in extreme 
cases as the feeding frenzy, has been observed 
in many species of sharks. In the blacktips and 
greys, the presence of more than one shark ap- 
peared to lower the threshold for the release of 
feeding behavior. 
Whitetips did not show this group effect. 
Even when feeding in numbers, members of 
this species responded individually and without 
a notable increase in excitement. The whitetip 
seemed to be relatively unresponsive to many 
of the stimulus situations which elicited a sharp 
reaction in the grey and blacktip. There was 
little overt response seen in this shark when en- 
countering a human in the water for the first 
time. In this situation we did not see the curi- 
osity frequently exhibited by the greys, nor 
the start and rapid flight usually exhibited by 
the blacktip. 
On several occasions whitetips appeared and 
took fish from the spears of divers before the 
fish could be removed from the water. Even in 
these instances, the slow, deliberate actions of 
this shark did not give the impression of being 
a threat to the diver. This impression may have 
been an illusion based on the sluggish behavior 
of the animal. On one such occasion a 6-ft 
whitetip bit the fish in half and then made a 
slow pass at the diver holding the other end of 
the spear. This appeared to be a warning pass 
at a potential competitor rather than an active- 
attack. Such warning passes were noted on sev- 
eral occasions directed at grouper or snappers 
which approached a bait that was under attack 
by a whitetip. Similar behavior was noted in- 
greys and blacktips. Tester (personal communi- 
cation) observed a small blacktip pursue a 
grouper of comparable size from a bait which 
had been placed on the bottom in shallow water 
near Aniyaani Island. In this case, the blacktip 
showed considerably more than a warning pass, 
as it actively pursued the grouper among a con- 
centration of small coral heads. We did not ob- 
serve these sharks exhibiting aggressive behav- 
ior toward members of their own species. One 
observation made on numerous occasions might 
at first glance seem to oppose this view. When 
a bait which was too large to be immediately 
swallowed was presented to a group of feeding 
greys or blacktips, the shark which succeeded 
in taking the bait would invariably swim rapidly 
away from the area, shaking its head vigorously 
from side to side presumably in attempts at 
cutting up and swallowing the bait. As it fled, 
Fig. 2. The blacktip shark, Carcharhmus melanopterm. (Photo by E. Hobson.) 
