Glow worms glow due to a chemical reaction called bioluminescence, which involves the molecule luciferin reacting with the enzyme luciferase, oxygen, and ATP to produce a blue-green light. They use this glow to attract prey insects towards their sticky silk threads, which then become trapped, allowing the glow worms to eat them. This light is a natural, sustained glow emitted by their bodies, serving primarily as a lure to capture food.

How Glow Worms Glow

Glow worms are actually larvae of fungus gnats. Their glow comes from a chemical process within their bodies where luciferin, an organic molecule, reacts with oxygen catalyzed by luciferase. This reaction emits light with very little heat, producing a visible blue-green glow.

Why They Glow

The primary purpose of their glow is to attract insects, which are prey. Flying insects are drawn towards the light and get stuck in the glow worms' sticky silk snares, similar to spider webs. The glow thus serves as a successful hunting tool in dark and humid environments like caves and forests.

Additional Notes

Different species of glow worms may have different structures for producing light, but all use similar bioluminescent chemistry. The glow also sometimes serves for mating signals in related species, but for glow worms, the main function is attracting prey.

In summary, glow worms glow to lure prey into their sticky threads by a biochemical light-producing reaction involving luciferin and luciferase.