The southern sand octopus can make a quick escape by making its own quicksand. How? It shoots jets of water into the sand grains, separating them into an almost fluid state, and allowing the octopus to burrow. There under the ocean floor, it hides from predators. This is likely a good thing for an octopus with no ability to camouflage. From New Scientist:
[Research article co-author Jasper] Montana and his team first caught the octopus in the act of burrowing in 2008 when they were scuba diving at night in Port Philip Bay, south of Melbourne, Australia. When they shone a light on the octopus, the startled animal spread out its arms and repeatedly injected high-powered jets of water into the sediment using its funnel… The liquefied sand is likely to reduce drag and so allow the animal to burrow more quickly, using less energy, Montana’s team speculates.Watch these next: Making Sand Swim, Deep Look’s The Amazing Life of Sand, and the classic octopus unscrews a jar from the inside.
They found that the animal used its arms and mantle to push the sand away and form a burrow. It also extended two arms to the surface to create a narrow chimney to breathe through. Finally, it secured the walls of its new home with a layer of mucus that kept the grains of sand together so the entire thing maintained its shape.