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The Sound of Science - 'Fireflies'

Welcome to The Sound of Science on WNIJ.

(P) We’re answering listener questions this month and today we have a great summer question. “How do fireflies light up?” Living in the Midwest, one of my favorite signs of summertime is seeing fireflies winking across the fields. How can fireflies light themselves up on command?

(K) Pati, that’s a great question! Fireflies are a local example of bioluminescence. Bioluminescence occurs when an animal or plant contains a type of compound called a luciferin. Luciferin (named after Lucifer, the light bringer) converts cellular energy to light in a complicated chemical reaction.

(P) Bioluminescence, I’ve heard of that. What is the difference between bioluminescence and say a light bulb?

(K) Fireflies produce light using chemical energy (in a chemical reaction) and lightbulbs produce light with electrical energy. The cool thing is fireflies convert 80-90% of their available cellular energy into visible light. An incandescent bulb only converts 10% of available electrical energy into visible light, the rest ends up as heat. Fireflies are said to create “cold” light. If fireflies were as inefficient as an incandescent bulb they wouldn’t survive the experience of lighting up, they would burn up from the heat they created.

(P) I love seeing the fireflies at night. Lighting yourself up certainly makes for a pretty summer evening light show, but why do fireflies light up?

(K) Well, like other shows of beauty in the natural world, fireflies light up to send a message. The light may signal predators that fireflies produce poisons, advertising that they are dangerous to eat. The light can also be used to attract a mate since each species has its own flash pattern.

(P) There is a lot happening when fireflies light up. It will make me think next time I see fireflies winking across a corn field.

(K) When I see a firefly light up at night I think of the complicated chemical reaction that is happening in its abdomen. Then, I smile and enjoy the show.

(P) Keep your questions coming by emailing them to stemoutreach@niu.edu.

(K) This is the Sound of Science on WNIJ, (P) where you learn something new every day.

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