Prawn larvae conceal their eyes with reflectors to hide from predators

To hide from predators, some crustacean larvae camouflage their black eyes with photonic glass that reflects light the same color as the water they inhabit.

To Alice Klein

Shrimp larvae hide from predators by camouflaging their black eyes with a light-manipulating material that reflects the color of the surrounding water.

Some sea creatures, such as jellyfish, glass squid, and ghost fish, have transparent bodies to avoid being spotted by predators. Eyes that contain pigment.

Benjamin Palmer and his colleagues at Ben-Gurion University of the Negev, Israel, investigated how transparent-bodied larvae of giant freshwater shrimp develop (macrobrachium rosen belgium) hides black eyes from predators.

They discover that their eyes are covered with photonic glass. Photonic glasses are materials with randomly arranged spherical particles with unusual optical properties. The larval eye structure reflects yellow-green light, matching the color of the turbid estuary in which the larvae live, suggesting that it aids in camouflage.

“The important thing is that the reflector color is the same from all viewing angles,” says Palmer. This is important to hide them from predators.

The team discovered that photonic glasses are made of nanospheres of a substance called isoxanthopterin. Using optical and electron microscopy, we confirmed that these nanospheres can rearrange themselves to produce slightly different shades of yellow and green. This could allow the larvae to move from shallow yellow water to deep green water while maintaining their disguise, says Palmer.

Researchers have since discovered that larvae of other crustaceans, such as shrimp, lobsters and crabs, also have reflectors that hide their eyes. These contain nanospheres of varying sizes, some made of isoxanthopterin and others of an as-yet-unidentified material, designed to reflect the appropriate color to match their surroundings. It is

For example, sea dwellers have reflectors that produce shades ranging from bright blue to silvery blue.

The isoxanthopterin nanospheres are very efficient at reflecting light, suggesting they may have industrial applications, says Palmer. “There is currently a great deal of interest in finding biocompatible high-refractive-index organic materials as substitutes for inorganic materials in pigments, cosmetics, and other optical materials,” he says.

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