This octopus summons quicksand to build a predator-proof bunker

It’s no secret that octopuses are the ocean's masters of camouflage, but the southern sand octopus (Octopus kaurna) found on the southern coast of Australia has a stunt that blows all other cephalopods out of the water!



Like a tiny molluscan magician, it hides by disappearing rapidly under the sand. Of course, we know that other octopus species can bury themselves, but Octopus kaurna's technique is one of a kind – and now it's been captured on camera for the first time!

The octopus uses its funnel (or siphon) to shoot jets of water into the sand beneath it, which creates quicksand. It then digs down with its arms and mantle up to 20 centimetres (around 8 inches) into the seabed, where it constructs a little burrow for itself, secreting mucus to reinforce the walls. As a finishing flourish, it pushes two of its arms to the surface to create a sort of "chimney" to breathe through.

Other octopuses may be able to hide in the sand, but they're forced to stay near the surface and must keep their funnels exposed in order to breathe. The southern sand octopus outmanoeuvres them all. “This is the first known cephalopod to burrow,” says Jasper Montana of the University of Melbourne, who first encountered the behaviour during a dive back in 2008.

If a predator happens to come across the buried octopus, it simply collapses its hiding place and uses the same quicksand technique to escape its attacker.

But why use these architectural acrobatics? The southern sand octopus lacks what others of its kind use for camouflage to hide from predators: tiny colour-changing organs known as chromatophores. Montana and his research team suspect those first-class burrowing skills may have evolved to make up for that.

h/t: New Scientist

Top header image: Anthony Pearson, Flickr