Octopuses, squid, and cuttlefish, the animals collectively known as cephalopods, are capable of the most incredible feats of camouflage. At a whim, they can change the colour, pattern, and texture of their skins to blend into the background, baffle their prey, or communicate with each other.

As if that wasn’t amazing enough, Lydia Mäthger and Roger Hanlon recently discovered that the common cuttlefish has light-sensitive proteins called opsins all over its skin. Opsins are the engines of sight. Even though animal eyes come in a wondrous variety of shapes and structures, all of them use opsins of one kind or another. The discovery of these proteins in cuttlefish skin suggested that these creatures might be able to sense