A team of researchers have attempted to find out how exactly fish can camouflage through the use of light while in the ocean. This study was highly valued from both a scientific point of view and also from the military point of view, because of the possibilities of applying this knowledge to various underwater machinery and forms of transport.
The team is comprised by researchers from the University of Texas in Austin and has discovered that two species of fish have developed through the evolutionary process the capability of reading and reflecting polarized light. The fish are able to do this through the use of microscopic structural formation found within their cells that reflect back polarized light. Polarized light is mainly light made out of light waves that travel in the same plane, and we can sometimes see it reflected in the water, as a sort of glare.
Studying the variation of polarized light found underwater is one of the three ways in which both the fish and our satellites can identify objects and threats, the other two being the difference in contrast and in color. Finding something through the use of polarized light variation detection is the most effective way out of the three numbered above.
The scientists conducted their studies in bays found in Florida and Curacao by using a video polarimeter, a machine that can see polarized light in the same way satellites and the fish themselves do. They essentially let the fish swim in one place while they revolved around him with the video polarimeter and a mirror, the mirror being used to compare the percentage of camouflage found in the fish.
The best fish when it came to this type of camouflage was the lookdown and the big eye scad, both having a higher degree of camouflage than the mirror itself, especially at 45-degree angles, known as the predatory angle. The predatory angle is in lamens terms the angle at which approaches the fish from either above or below the fish’s axis.
The next step in this study is to see how exactly do the fish manipulate their camouflage, and even if they do it at all. Two possibilities are at the moment the most plausible. They can either control the microstructures in their cells in order to manipulate the angle in which polarized reflects off them, or they just shift their swimming angle.
By seeing this, scientists will be able to further understand the way through which the fish actually attains its almost complete invisibility underwater. It’s safe to say that the discovery will more than likely attract the attention of the US Navy who up to this point have only been capable of achieving sonar invisibility.
By knowing exactly how fish can camouflage through the use of light, more specifically polarized light, the military application of these findings is almost priceless. Just imagine, a submarine which is both invisible to a sonar and at the same time invisible to both the naked eye and the satellites which roam above.