Rainbow Roll

Chameleons and kelp – what do they have in common?

This is Sandra Tsing Loh with the Loh Down on Science.

Chameleons change colors to hide or to express their feelings — like living mood rings! But seaweed doesn’t change color… or does it?

Meet Heather Whitney from the University of Bristol. Her team identified a brown alga that shimmers blue in dim light. Shine more light on it and the blues fade away! To find out why, they used powerful microscopes to peek inside the seaweed’s cells.

There, they found mirrors made of tiny oil droplets packed together. This kind of structure is called a photonic crystal. Chameleons have photonic crystals in their skin. But why would seaweed need to change up its look?

Scientists think the alga uses them like transition lenses. Changing tides affect the amount of available sunlight where this alga grows. When it’s dim, the mirrors turn on. The mirrors reflect blue as the seaweed absorbs all other colors. When it’s bright, the mirrors turn OFF to prevent overheating.

Copying nature’s color-shifting mechanism could lead to new ways to reduce our energy bills.

And maybe even… Color changing sushi rolls?