Shrimp larvae are alone and exposed while floating in the open ocean, just like jellyfish. They need to master being invisible to keep themselves hidden and safe from predators.
Hiding their bodies is no sweat as they have a transparent frame, but their eyes make it challenging to attain true invisibility.
Shrimp Larvae Hides Their Eyes With Disco Eye-Glitter
Although they have dark eyes, shrimp larvae make it possible to keep themselves invisible by completely camouflaging their eyeballs with glittery eyeshine that blend in with different shades of blue-green ocean water. The eyeball-shielding invisibility involves the glittering "disco eye-crystals."
Keshet Shavit, the master's student who discovered the disco eye crystals, told Slate that disco balls are made of crystalline isoxanthopterin. They are flat features that create something with a core inside, and the small nanospheres or small disco balls are efficient in reflecting light.
Johannes Haataja, a computational researcher from the University of Cambridge, created a model to simulate how they work. According to him, a reflector is a few micrometers of the optical spheres. When the diameters of the particles are tuned in, depending on how densely they are packed, one will get a certain color response. However, it's difficult to predict the type of structures needed for a specific color response.
Johannes was able to recreate this biological cell in a computer and then calculate how light travels through it, which was an awe-inspiring feat, said Benjamin Palmer, whose chemistry lab at the Ben-Gurion University of the Negev in Israel decided to look into the optics of crustacean eyes. It is called a photonic crystal when all of these particles are arranged in very close proximity and in an orderly fashion. It results in the iridescence, similar to how peacock feathers appear purple from one angle and green from another.
In the baby shrimp's case, however, the photonic glass - where the particles are relaxed and not crammed together - lacks iridescence. So, the color is uniform from all perspectives. This is essential for the function of this camouflage.
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Crustaceans Larvae Have Eye Reflectors
According to New Scientist, the researchers discovered that the larvae of some crustaceans, including shrimps, lobsters, and crabs, have reflectors to keep their eyes hidden. It contains different-sized nanospheres; some are made of isoxanthopterin, while the other materials are not yet identified.
The reflectors allow them to reflect the right color that matches their surroundings, keeping their black eyes invisible. Sea creatures with reflectors produce shades ranging from bright blue to silvery blue.
According to Palmer, since isoxanthopterin nanospheres are so effective at reflecting light, they may have industrial applications. He added that there is significant interest in discovering organic, biocompatible, high-refractive-index materials to replace inorganic materials in pigments, cosmetics, and other optical materials.
During the interview with Slate, they were asked for an exciting application of their discovery.
Shavit thought of nail polish. According to him, using the mechanism, one will not need a thick layer of paint but a thin layer of nano disco balls to achieve a consistent color.
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