There are two ways of becoming invisible: you can either be transparent so all light passes through your body, or you can blend in by taking on the colours of your surroundings. A truly incredible animal would be able to do both, switching between the two at a whim. And that’s exactly what some squids and octopuses can do.

Both species live in the twilight zone, a band of water between 600 and 1000 metres down. Sunlight only just grasps at this world, which teeters on the edge of total darkness. The animals that live here face unique challenges if they want to stay hidden.

Transparent animals are never perfectly transparent (although Japetella does a pretty good job; see below). Most