ACTIVITY INDEX 
166 
PACIFIC SCIENCE, Vol. XVII, April 1963 
STARVED 
BLACKTIPS 
QUIESCENT A6ITATE0 
GROUPER GROUPER 
WATER WATER 
I I I i ! L I I 1—1 L 
0900 0912 
TIME - CONTROL AND TEST PERIODS 
Fig. 10. Activity index during successive 2-min periods, illustrating response of starved grey sharks to 
"'quiescent grouper water” and of starved blackdp sharks to "agitated grouper water.” 
shark was positive but less intense. "Tilapia 
water” was the attractant used in the experi- 
ment involving human sweat which was de- 
scribed earlier. 
Several, more definitive experiments were 
conducted at Eniwetok during the summer of 
I960 using an experimental arrangement illus- 
trated in Figure 9. Living fish were placed in 
a 2 5 -gal plastic container into which sea water 
was flowing. The sea water could be siphoned 
from the container into the test area of either 
Tank 1 or Tank 2, or it could be spilled to the 
ground. The compartment of Tank 1 contained 
four starved blacktip sharks and that of Tank 
2 held four starved grey sharks, all with normal 
vision. One observer, manipulating the siphons 
and living "prey” fish, was concealed from the 
sharks by a blind; a second observer, recording 
data on shark behavior, was concealed in the 
observation booth. 
Only two of several experiments will be de- 
scribed in detail. In one (Fig. 10), four group- 
ers ( Epinephelus merra ) had been placed in the 
container the previous night, with the water 
siphoning into the blacktip compartment. In 
the morning, following a series of control peri- 
ods which started at 0830 (timed on a 24-hr 
clock ) , the "quiescent grouper water” was siph- 
oned into the grey shark compartment. In the 
first test period (at 0842) the grey sharks 
