Misfit Scales Emit Brighter Light

Biological Strategy

Firefly

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Distribute Energy

Many forms of energy are naturally available, including kinetic, potential, thermal, elastic, radiant, chemical, and more. All living systems require energy to carry out their many activities. Energy isn’t a physical object that can be held, so it also can’t be pushed, pulled, or carried. However, it can be transmitted or transformed. For example, the golden-scale snail has a tri-layered shell that dissipates, or transfers, forces from a predator biting down on it, thereby minimizing damage to its soft body inside the shell.

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Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

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The scales of the Phoruris firefly emit more light because misfit between scales increases the number of visible light beams.

When a light beam hits a surface, the amount of visible light depends on the angle that the beam takes when approaching that surface. In the case of the Photuris firefly’s scale, a light beam hitting between 40?-90? will reflect more light than it emits. Light beams hitting at 90? or higher will make the light more visible and brighter to the observer. The 10µm long by 3µm high slanting structure creates different angles, repeating 90?, 180?, and 270?, for the light beam to hit at different parts of the scale. This allows the light beam to hit the scale above the 40?-90? region, so that all of the light beams hitting the scale can contribute to the visible light. The emittance of light at multiple angles creates multiple beams from the same original source. These beams add onto each other to contribute to greater brightness.

This strategy was contributed by Rachel Major

Last Updated September 14, 2016

References

Journal article

Improved light extraction in the bioluminescent lantern of a Photuris firefly (Lampyridae)

Opt. Express | 09/01/2013 | Annick Bay, Peter Cloetens, Heikki Suhonen, Jean Pol Vigneron

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