For the octopus and cuttlefish, instantaneously changing their skin color and pattern to disappear into the environment is just part of their camouflage prowess. These animals can also swiftly and reversibly morph their skin into a textured, 3D surface, giving the animal a ragged outline that mimics seaweed, coral, or other objects it detects and uses for camouflage.
This week, engineers at Cornell University report on their invention of stretchable surfaces with programmable 3D texture morphing, a synthetic “camouflaging skin” inspired by studying and modeling the real thing in octopus and cuttlefish. The engineers, along with collaborator and cephalopod biologist Roger Hanlon of the Marine Biological Laboratory (MBL), Woods Hole, report on their controllable soft actuator in the October 13 issue of Science.
Led by James Pikul and Robert Shepherd, the team’s pneumatically-activated material takes a cue from the 3D bumps, or papillae, that cephalopods can express in one-fifth of a second for dynamic camouflage, and then retract to swim away without the papillae imposing hydrodynamic drag.
“Lots of animals have papillae, but they can’t extend and retract them instantaneously as octopus and cuttlefish do,” says Hanlon, who is the leading expert on cephalopod dynamic camouflage. “These are soft-bodied molluscs without a shell; their primary defense is their morphing skin.”
Papillae are examples of a muscular hydrostat, biological structures that consist of muscle with no skeletal support (such as the human tongue). Hanlon and…