Crystal Cells (Insect Blood Darkeners)

Round cells with crystals

Crystal cells float in the blood of insects like fruit flies. Scientists study them most in fruit fly larvae, the little wiggly babies that grow into flies.

A crystal cell is small and round. Inside are one or more crystals. The crystals are not rocks. They are made of a helper chemical called an enzyme, packed tightly together.

Only a few of a larva's blood cells are crystal cells, but they have an important job.

Burst, darken, and seal

When an insect gets a scrape, its crystal cells burst open. The crystals spill out and turn into working enzyme.

• The enzyme makes a dark color called melanin, so the blood near the wound turns dark.
• It helps the blood get thick, which plugs the hole, a bit like your platelets do.
• It also helps stop germs.

Crystal cell quiz