for National Geographic News
The ability of bats and dolphins to see at night and navigate the murky depths of the sea has long garnered the interest of the United States military.
"We would like to emulate this capability for the quick, accurate detection and classification of buried mines," said Harold Hawkins, a program manager with the biosonar program at the Office of Naval Research in Arlington, Virginia.
Hawkins and his colleagues seek to understand how bats and dolphins make sounds and process the sounds' echoes to create three-dimensional reconstructions of objects in their environment.
Reception of echoes is the basis of conventional sonar systems designed by humans. But many of these devices are not nearly as sophisticated as the ones that have evolved in bats and dolphins, according to James Simmons, a neuroscientist at Brown University in Providence, Rhode Island.
Simmons studies the biological sonar systems of bats and cooperates with people who study dolphins in the Navy Marine Mammal Program in San Diego, California. The collaborative research is funded in part by the Office of Naval Research.
"The Navy has a problem with mines," said Simmons. "They are easy and cheap to get and they can damage or sink a large ship."
Naval mines are designed to float on the surface of the sea or are moored just below its surface to blow up ships. Other types can be planted on the seafloor or hidden among rocks to cripple submarines.
The Navy currently uses trained dolphins to help detect mines. The dolphins are carried in holding tanks on warships and released upon entering mine-infested waters. The dolphins use their sonar to find the mines and later communicate that information to sailors.
One goal of the Office of Naval Research's Biosonar Program is to build a sonar system as good as the dolphins. Simmons' research on bats is crucial to the success of the program.
"Since bat work has a large and formal foundation in neurophysiology and the neuronal wiring of the bat is more or less well understood, the hope is that similar echolocation performance by bats and dolphins may have roots in similar neurophysiology," explained Patrick Moore, a researcher with the Navy Marine Mammal Program.
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