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PACIFIC SCIENCE, VoL XVII, April 1963 
Fig. 1 . View of shark tanks at Eniwetok Marine Biological Laboratory. (Photograph by Atomic Energy 
Commission.) 
from the lagoon at a maximum rate of flow of 
about 10 gal per min. Lying side by side with 
a common middle wall, the tanks were 50 ft 
long, 4 ft wide and 3 ft deep with turning 
basins 6 ft in diameter at both ends (Fig. 2). 
The tanks could be divided into 5 -ft sections 
by gates which slid in notches in the walls. Thus 
the sharks could be confined in a compartment 
consisting of one or several sections. Observa- 
tion booths located midway along the tanks on 
both sides or blinds erected elsewhere effectively 
concealed the observer from the sharks. 
Olfaction tests were conducted on both "nor- 
mal” and blinded sharks. The sharks were 
blinded after anesthesia in a 1/1000 solution 
of MS 222- Sandoz (cf Gilbert and Wood, 1957) 
by coagulating the proteins of the aqueous hu- 
mor with the diode probe of a "Hyfrecator” in- 
serted through the cornea. Proof of blindness 
was lack of response to a hand waved close to 
the surface as they swam by or lack of response 
to the beam of a flashlight directed at their eyes. 
Within 1 hr after recovery from anesthesia the 
sharks circled their compartment, guided by the 
tip of the outstretched pectoral fin which 
touched the wall. Within a day they were able 
to circle the compartment without this tactile 
aide. They soon fed avidly on pieces of fish, 
squid, or other food which settled to the bottom 
before it was eaten. The sharks would detect 
the odor while swimming in mid-water and 
would spiral down, converging on the food by 
swimming in a figure-8 pattern on the bottom. 
Our attempts at blinding sharks with contact 
occluders (Mishkin, Gunkel, and Rosvold, 1959) 
were unsuccessful, perhaps because of faulty 
technique in molding plastic "lenses” and fitting 
them to the eyes. In general, the response of 
