Lesson 1
A lantern made of cells
A firefly is a kind of beetle. Near the end of its body is a glowing part called the lantern.
The lantern is packed with light cells. Scientists call them photocytes, which means "light cells".
- A see-through window of skin lets the light shine out.
- Behind the light cells is a layer of white cells that works like a mirror. It bounces the light outward so it looks brighter.
- Tiny air tubes bring air right up to the light cells.
Try thisScroll up to the 3D model and press Light up! to see the light cells glow.
Lesson 2
Light from a chemical reaction
Inside each light cell, three things meet:
- Luciferin, a chemical that can give off light.
- Luciferase, a helper that makes the reaction happen.
- Oxygen from the air tubes.
When they come together, the cell gives off light. This is called bioluminescence: light made by a living thing.
The firefly can turn its light on and off by controlling how much oxygen reaches the light cells.
Try thisPress Send in air to watch oxygen travel down the air tubes to the light cells.
Wow!Firefly light is called cold light. Almost all of the energy turns into light, so it hardly makes any heat. A firefly's lantern does not feel hot at all.
Lesson 3
Blinking to say hello
Fireflies use their light to talk. Each kind of firefly has its own flash pattern, like a secret code. Some blink fast, some blink slow, some blink a few times in a row.
A firefly flies around flashing its code. A firefly of the same kind answers with a flash, and that is how they find a mate.
Try thisGrab a flashlight and a friend. Make up your own flash code, like two quick blinks and one long one. Can your friend answer with the right code from across a dark room?
Wow!Glow sticks also make cold light with a chemical reaction. Fireflies were doing it first!