ACTIVITY INDEX 
Olfaction and Sharks — Tester 
167 
showed obvious awareness and mild attraction, 
with one shark biting the siphon tube, but the 
response quickly subsided. Siphoning into the 
blacktip compartment was then resumed (at 
0900) with no noticeable response from the 
sharks; this was anticipated as the water had 
been siphoning into this compartment all night. 
The groupers were then frightened and excited 
by threatening them with a moving stick. There 
followed a noticeable hunting reaction by the 
blacktips (at 0912), stimulated by the "agi- 
tated” grouper water. Similar results were ob- 
tained with both starved blacktip and grey 
sharks using quiescent and agitated surgeon fish 
and mullet in place of the groupers. 
In the second experiment to be described in 
detail ( Fig. 11), the grey sharks showed a nor- 
mal behavior pattern during control periods 
which started at 1600. When "quiescent grouper 
water” was introduced (at 16 12) they responded, 
as above, with a mild hunting reaction; one bit 
the tube and others milled near it. In the mean- 
time, a small grouper had been removed from 
the aquarium and held in a dip net in air for 
30 min, at which time it was still alive and ap- 
parently undamaged. Wth the water from the 
quiescent groupers still flowing into the grey 
shark compartment, the "distressed” grouper 
was quietly lowered into the container (at 1622) 
by a string tied around its body; it was removed 
after the third test period (1628). The sharks 
displayed a violent hunting reaction with cir- 
cling and biting of the tube. The "quiescent 
grouper water” continued to siphon into the 
compartment for about 1 hr, at which time 
(1730) the sharks exhibited normal activity 
during control conditions. The small grouper 
which had been returned to the dip net and was 
still alive after 74 min, was again lowered into 
the container (at 1740) for three test periods. 
Fig. 11. Activity index during successive 2-min periods, illustrating response of starved grey sharks to 
"quiescent grouper water,” to "distressed grouper water,” and to "dead grouper water.” 
