Cryptochrome is a light-sensitive protein found in both plants and animals. In plants, it helps regulate growth in response to light. In animals, from butterflies to humans, it helps keep internal clocks in sync and, in some species, acts like a built-in compass, sensing Earth’s magnetic field.

First discovered in 1993 by Dr. Margaret Ahmad and Anthony Carshmore for its role in circadian rhythms, cryptochrome gets its name from the Greek words for “hidden” and “color.” It helps organisms know when to sleep, eat, migrate, or bloom.

But in some animals, it does more than keep time. When struck by certain wavelengths of light, especially blue light, cryptochrome can trigger a reaction between two electrons that may become quantum entangled. 

This subtle shift makes the protein sensitive to Earth’s magnetic field, offering a kind of internal compass.

Cryptochrome is widespread across the animal kingdom:

• Birds: Migratory songbirds, pigeons, chickens

• Insects: Honeybees, monarch butterflies, fruit flies

• Marine life: Salmon, sea turtles

• Mammals: Humans, mice, bats, dogs

• Reptiles: Certain lizards and snakes

For a robin, it might mean finding the right continent. For a monarch butterfly, it’s a guide across thousands of miles. And for humans, it may be a hidden sense we’re only just beginning to rediscover.