Biology Reference
In-Depth Information
PIONEERING DOLPHIN RESEARCH
With Ken Norris as curator, Marineland was an active research
facility in the early 1960s. It was already known that dolphins emit-
ted rapid bursts of sound in the form of clicks that were believed
to enable them to navigate and detect objects underwater. This
was similar in function to the echolocation used by bats at night.
Unknown, though, was how sensitive this sonar is, and how much
the dolphins rely on it compared to sight. So Ken and his assis-
tant John Prescott set out to scientifically and methodically in-
vestigate the sonar capabilities of dolphins.
A young female bottlenose dolphin named “Kathy” was the test
subject. She was trained to accept soft latex rubber cups (mod-
eled after “falsies”) being placed over her eyes to function as a blind-
fold. Without her use of sight, Kathy would have to rely solely
on sound. The training took considerable patience and time, but
through positive reinforcement, Ken and John gradually gained
her trust. Eventually, wearing her two latex blindfolds, Kathy was
able to swim around her tank just as well as if she were seeing
with her eyes. The speed at which she found mackerel tossed into
the tank was no di¤erent when she was blinded than when she
could see.
The next step was to find out just how sensitive her sonar was.
Smaller and smaller pieces of food were used, and she still had no
trouble finding them. She could even tell one species of identi-
cally sized fish food from another just by the sonar image she re-
ceived. A tiny BB pellet was dropped twenty feet away on the far
side of her tank, and she was able to quickly locate it. The con-
clusion drawn from these elegant experiments was that bottle-
nose dolphins have a truly extraordinary underwater navigation
system that is at least as acute as their sight.
 
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