Comic books and movies have us dreaming of invisibility, and scientists are even working really hard to bring us real life invisibility cloaks (but they will probably never be as good as Harry Potter’s). But did you know that there’s a truly awesome little animal out there that has pipped us to the invisibility post?
Known as sea sapphires, these miniscule aquatic crustaceans have been described as “the most beautiful animal you’ve never seen,” and it’s easy to see why. In certain members of the Sapphirina genus, the males are able to put on a spectacular disco effect, shimmering in brilliant blues, fiery reds or glittering golds. And then they vanish, seemingly effortlessly, in an instant. New research, published in the Journal of the American Chemical Society, is revealing the secrets to this fancy trick, and it could spawn a new generation of optical technologies.
Scientists already knew that their sparkling colors were due to the presence of hexagonal-shaped guanine crystals – the same things that help chameleons to rapidly change color – which are layered between a gel-like substance called cytoplasm. The thickness of the cytoplasm layer, and thus the space between the crystal layers, turns out to be key in determining which wavelengths of light they reflect, and hence what color they appear to be.
Using scanning electron microscopy to characterize the organization of the layers, they discovered that while the thickness of the crystal plates was pretty much uniform among different colored specimens, the cytoplasm ranged between 50 and 200 nanometers thick. In addition, the color of these copepods was also dependent on the angle at which light strikes the crystals. And should that angle be 45 degrees, the light reflected shifts from the visible range to the ultraviolet. Ordinarily, our eyes filter out UV wavelengths, which is why these tiny animals can seemingly disappear in a flash.
“An intriguing question that still remains is whether the differences in color are genetic and each male is born with a defined color, or whether they can control the reflected color,” said lead researcher Lia Addadi, from the Weizmann Institute of Science in Rehovot, New Scientist reports.
Something else that the researchers think could be worth pursuing is using these new findings to guide the design of a new wave of optical technologies, for example reflective coatings or optical displays. There is no mention of an invisibility cloak, but here’s hoping anyway.
Check out a video of the copepods in action here: