U.S. to develop 'stealth shark'

Remote-controlled: the spiny dogfish, Squalus acanthias

Biologists have developed a neural implant which can be used to 'steer' spiny dogfish, a technique which the U.S. military now hopes to build on to produce 'stealth sharks.'

The implant, consisting of a series of electrodes embedded in the olfactory (smell) region of the dogfish brain, is the work of Jelle Atema and his team at Boston University. Radio signals from a laptop can stimulate the brain of the dogfish, fooling it into believing that there is an attractive odour in a particular direction, which it then turns towards.

Atema is using the implants to try and determine how the shark brain interprets chemical signals to obtain information about the environment. Sharks have sophisticated nervous systems which allow them to detect not just odours but also electrical impulses generated by other organisms, enabling them to locate prey. It is also believed that sharks use their electroreceptors to detect the earth's magnetic field, so that they can navigate through the water over long distances.

With funding from the Pentagon, the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Virginia, is now developing a similar implant to remotely guide sharks so that they can stealthily follow enemy vessels and provide information on their position and movements.

The implant developed by DARPA researchers contains wires which sink into the shark brain to record the activity from many nerve cells, or neurons, simultaneously. It is hoped that the implant can help them to determine the patterns of neural activity when the shark detects an odour, current or electrical field. The team also plans to program a microchip which can recognize these patterns.

Researchers at the Naval Undersea Warfare Center described the implant in the abstract for their presentation at the 2006 Ocean Sciences Meeting in Honolulu, Hawaii.