Life in the wild can be tough, and for many animals, the best way to survive is by hiding from predators in plain sight. One of nature’s most impressive masters of disguise is the octopus, which can change color and texture in less than a second, blending into its surroundings with incredible accuracy. Case in point: this octopus, which surfaced online this week.
We spoke with Ernie Sawyer, a senior aquarist at the Shedd Aquarium in Chicago and caretaker of the aquarium’s 2-year-old Giant Pacific Octopus, Oliver, to learn a bit more about what this eight-legged creature is up to.
What kind of octopus is this?
“It looks like it’s one of many dozen tropical saltwater species,” Sawyer says. “And looks like a pretty good size one—its total length across is maybe a foot and half to 2 feet.” Indeed, according to the diver, who posted the original video on YouTube, he was snorkeling in the Caribbean when he dove down to get a closer look at a shell. “As I approached the octopus came out of hiding. I had literally no idea he was there until I was about a metre away.” Sawyer says most octopuses have this unique camouflage skill.
Why do octopuses (not octopi!) disguise themselves?
“Octopuses are really secretive by nature,” Sawyer says. “They like to try to blend into their surroundings if they’re not in some kind of cave or den.” They can also use their disguises to either avoid predators or to sneak up on their own prey.
How do they know what color to mimic?
Good question, and one that researchers are still trying to answer. They know Cephalopods (octopuses, squids, and cuttlefish) match their skin to their surroundings using their eyesight. But what’s perplexing is that octopuses are actually colorblind. It’s possible they can distinguish between different polarization of light better than humans can, but the exact method for how they identify color is unknown. The act of changing color is the work of cells called chromatophores that contain colorful pigments (black, brown, orange, red, or yellow) and can be squeezed like a balloon to make the pigments more prominent on the skin. Fox Meyer with the Smithsonian Museum put it well: “If you squeezed a dye-filled balloon, the color would be pushed to the top, stretching out the surface and making the color appear brighter.”
Marine biologist Roger Hanlon has actually identified three to four basic pattern templates cephalopods use most often: uniform (no contrast in pattern), mottle (light and dark splotches), and disruptive (obscures the outline of the animal to confuse its identity). Here’s a great image showing examples of those three:
And they can change texture, too?
Yes! Cephalopods are the only type of animal known to control the texture of their skin to create spikes, bumps, and ridges. Sawyer says Oliver, the Shedd Aquarium’s octopus, does this from time to time. Here’s a closeup of this process in action:
Why does the octopus turn electric blue when approached?
Actually, it’s probably not turning blue at all—it just appears that way under water. “It’s probably a whitish grey,” says Sawyer. “It might look blue in video, but by turning white, it is trying to make itself look bigger and more of a menace to the approaching diver.” Most octopuses are naturally “brownish tan, like a khaki,” he says.
Here’s one more incredible video: