萤火虫为何会发光?

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This week on Why? Tell Me Why! We are answering a viewer question as to why lightning bugs² light up.

Lightning bugs light up basically to find a mate. It’s a way that lightning bugs communicate witheach other, to call each other together, because someone’s looking for a mate. They have thesefeatures in the abdomen³ of the body: they light up and they can control when they light up, whenthey blink and how long they blink. And they use that blinking signal to attract each other.

Do both males and females have the lights?

They both have the lights, but the females have brighter lights and bigger lights because they arethe ones who are trying to attract males to them. Each different species of lightning bug¹ has adifferent pattern of flashing to only attract its own species. In this way, if there are fivedifferent species of lightning bugs all in the same field, they can tell who is their same speciesand who is not. So, they know who to be attracted to. There is an enzyme⁴ in these insects calledluciferase. And it uses something that insects make from the food they eat to bind⁵ together andgenerate light with very little heat. So, one of the interesting things about fireflies is theygenerate this light without making heat.

The only time we see lightning bugs lighting⁶ up is when they are on a quest to find a mate? That’sa, that’s one time they'll use their lights?

There is one other time when lightning bugs will use their lights and that is there is one speciesof lightning bugs that uses the light to attract other lightning bugs which she will aim to eat.

 

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