Crustaceans use a photonic glass of crystal nanospheres to cover their eyes. they can effectively camouflage themselves by changing their color. Deep-ocean inhabitants such as jellyfish, squid, and shrimp have bodies so translucent to light that predators hardly notice them. Since living things normally have to preserve eye pigments that make them recognizable in order to have functional vision, their eyes are an element that can reveal their presence in their bodies. Researchers have now discovered a way for crustaceans to circumvent this problem: they coat the pigment with a refractive photonic glass made up of crystalline nanospheres.
Organisms can adjust nanosphere diameters to accurately reflect the hazy environment.
To stay hidden, animals can adjust the diameters of the nanospheres to accurately reflect the turbid blues, yellows and greens of deep water.
For their study, Keshet Shavit of Israel's Ben-Gurion University of the Negev and colleagues examined the eyes of a huge freshwater shrimp, Macrobrachium rosenbergii, as well as a large number of larval crustaceans, including shrimp, lobster and crab larvae. All the animals studied had transparent bodies and vividly colored eyes. To freeze each creature's eyes, the scientists used a known flash-freezing technique, which preserves the eye structure, and then split each eye in half to gain access to the internal structures.
Scanning Electron Microscope
Cryogenic scanning electron microscopy, a method that allows high resolution imaging of samples at extremely low temperatures, was then used to view the samples.
The scientists discovered a 3m-thick layer of spheres with a diameter of several hundred nm encapsulated in the eyes of the organisms they studied. These “photonic glass” formations are known to selectively reflect visible light, giving buildings vibrant hues. The research team discovered that different shrimp species have different sizes of eye nanospheres. In theory, this diameter should correlate with the true "eye glare" color of each species. The research team also discovered that shrimps can change how organisms appear by changing the size and arrangement of nanoparticles surrounding their eyes.
Similar results were discovered for other crustaceans the team studied. For example, one type of shrimp has a green-yellow eye during the day and a yellow eye at night. The team's simulations show that the color change is due to a decrease in the degree of irregularity in nanoparticle packaging, which was revealed by cryo-SEM examination of this species' eyes.
According to Shavit's research, the process by which crustaceans regulate the size and arrangement of nanoparticles is not yet known. Future research by the researchers will address this issue. Biologist Kate Feller of Union College in New York can't wait to learn the results of these studies.
According to Feller, “These luminous, reflective structures are very clearly advantageous for camouflaging in the open ocean.” “But each of these species appears to use a different mechanism. I'm really looking forward to learning more about it.
One of the team members, Johannes Haataja, a postdoctoral researcher at the University of Cambridge in England, states that the high refractive index of the eye structures detected makes them interesting from a material point of view. Because of their ability to enable the creation of systems with vibrant colors, highly reflective materials are important for a variety of technologies, including cameras, car paints and cosmetics.
However, since most highly reflective materials such as titanium dioxide are inorganic, there are concerns about their toxicity. According to Haataja, the crustaceans are “inspiring how to make these [shattering] colors using organic, environmentally safe materials.”
Source: physics.aps.org/articles/v16/48
Günceleme: 24/03/2023 11:53