The Skin That Sees

The fourth morning, Chiara had a colour test. She put three plates on the tank floor. Red. Blue. Yellow.

Under one plate, a piece of shrimp was hidden. Today it was under the red plate.

"Octopuses are colour-blind," Chiara said. "Their eyes cannot tell colours apart."

"But watch," she said.

Pasta uncurled. Two arms went out. They passed over the blue plate. They passed over the yellow plate. They stopped over the red plate. One arm lifted it. Pasta took the shrimp.

"She is not blind to colour," Chiara said. "But it is not her eyes that see it."

Scientists have learned that octopus skin can sense light. The same kind of cells that are in human eyes are in octopus skin. The skin can see colours.

This is how a colour-blind animal can copy the colours of coral and sand. The eyes do not see the colours. The skin does.

Polly walked slowly along the rim of the tank. She had never thought about her own eyes. The idea that an animal could see with its skin was very strange.