US researchers have developed an underwater GPS device inspired by the unique vision of the prawn mantis, capable of independently moving each of its eyes and capturing a range of very high spectroscopy, according to a study published in the journal Science Advances.
This technology, according to the authors, opens new possibilities for underwater navigation and understanding of the migratory behaviour of animals on the seabed, which is difficult for the human eye to see. The camera, a variation of a polarization imaging generator called ‘Mantis Cam’ by the prawn that inspired its operation, exploits the way light refracts when it passes through the surface of the water and bounces off particles and molecules of water. “We collected underwater polarization data from around the world with marine biologists and noticed that water polarization patterns were constantly changing,” said study lead author Viktor Gruev, a professor at the University of Illinois ( USA ).
Gruev’s team determined through laboratory tests that the underwater polarization patterns are a result of the position of the sun in relation to the location where the recordings were obtained. In addition, he discovered that they can use the submarine polarization patterns to estimate the direction of the sun and the angle of elevation, which allows them to know their GPS coordinates when they know the date and time of filming. “We tested our submarine GPS method by combining our camera with an electronic compass and tilt sensor to measure underwater polarization data at a variety of sites around the world, depths, wind conditions and times of day,” said Gruev, who said that he and his colleagues were able to locate their position with a precision of 61 kilometers.
This technology can open new ways for people and robots to navigate better underwater, using visual signals of polarized light. Among other applications, this GPS could be used to find traces of fallen aircraft in the ocean or to create a detailed map of the seabed. This research could also lead to new knowledge about the migratory behaviour of many marine species. “Animals like turtles and eels, for example, probably use a lot of sensors to navigate their annual migration routes that take them thousands of miles across the oceans,” the scientist continued.
These sensors may include a combination of magnetic, olfactory elements and possibly, as Gruev’s research suggests, visual signals based on polarization information. Another aspect of this technology is its potential to help researchers understand how pollution can alter the migratory routes of animals sensitive to polarized light. “It is very likely that the increase in pollutants in the air and water will alter the patterns of underwater polarization, making the submarine environment look different from what many animals have learned,” concluded Gruev.