The octopus on the sock

The rust-coloured sock in the Deep Water Guardian trio carries an octopus, with a row of shells knitted around the cuff. Here is the animal behind it.

Three hearts and blue blood

The common octopus lives from the rock pools down to around 180 m, on the continental shelf. It has three hearts: two push blood through the gills, one pushes it round the body. Its blood is blue, because it carries oxygen with copper where ours uses iron. It has no bones at all, which is why an octopus can pass through any gap wider than its beak, the one hard part of its body.

A short life

Most common octopuses live for one to two years. In that time they learn to open jars, change the colour and texture of their skin in a fraction of a second, and squeeze into places that seem far too small. Off Western Australia they live on reefs and in seagrass, in the same water as the turtle and, further north, the whale shark.

On the sock

The octopus is knitted in rust, as part of the fabric rather than printed on it, so the picture keeps its shape and colour wash after wash. The yarn is 85% cotton, 12% nylon and 3% elastane, and one size fits most adult feet. The octopus sock is sold on its own or in the trio, on the Deep Water Guardian socks page. Every order is posted from Perth with Australia Post; here is how long that takes, state by state.