Explaining This Octopus' Amazing Camouflage Skills

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:

Andreas Trepte via Wikimedia Commons // CC BY-SA 2.5
Climate Change Has Forced Mussels to Toughen Up
Andreas Trepte via Wikimedia Commons // CC BY-SA 2.5
Andreas Trepte via Wikimedia Commons // CC BY-SA 2.5

Researchers writing in the journal Science Advances say blue mussels are rapidly evolving stronger shells to protect themselves against rising acid levels in sea water.

Bivalves like mussels, clams, and oysters aren’t good swimmers, and they don’t have teeth. Their hard shells are often the only things standing between themselves and a sea of dangers.

But even those shells have been threatened lately, as pollution and climate change push the ocean's carbon dioxide to dangerous levels. Too much carbon dioxide interferes with a bivalve’s ability to calcify (or harden) its shell, leaving it completely vulnerable.

A team of German scientists wondered what, if anything, the bivalves were doing to cope. They studied two populations of blue mussels (Mytilus edulis): one in the Baltic Sea, and another in the brackish waters of the North Sea.

The researchers collected water samples and monitored the mussel colonies for three years. They analyzed the chemical content of the water and the mussels’ life cycles—tracking their growth, survival, and death.

The red line across this mussel larva shows the limits of its shell growth. Image credit: Thomsen et al. Sci. Adv. 2017

Analysis of all that data showed that the two groups were living very different lives. The Baltic was rapidly acidifying—but rather than rolling over and dying, Baltic mussels were armoring up. Over several generations, their shells grew harder.

Their cousins living in the relatively stable waters of the North Sea enjoyed a cushier existence. Their shells stayed pretty much the same. That may be the case for now, the researchers say, but it definitely leaves them vulnerable to higher carbon dioxide levels in the future.

Inspiring as the Baltic mussels’ defiance might be, the researchers note that it’s not a short-term solution. Tougher shells didn’t increase the mussels’ survival rate in acidified waters—at least, not yet.

"Future experiments need to be performed over multiple generations," the authors write, "to obtain a detailed understanding of the rate of adaptation and the underlying mechanisms to predict whether adaptation will enable marine organisms to overcome the constraints of ocean acidification."

University of Adelaide
Scientists Find Potential Diabetes Drug in Platypus Venom
University of Adelaide
University of Adelaide

The future of diabetes medicine may be duck-billed and web-footed. Australian researchers have found a compound in platypus venom (yes, venom) that balances blood sugar. The team published their results in the journal Scientific Reports.

So, about that venom. The platypus (Ornithorhynchus anatinus) may look placid and, frankly, kind of goofy, but come mating season, the weaponry comes out. Male platypuses competing for female attention wrestle their opponents to the ground and kick-stab them with the venom-tipped, talon-like spurs on their back legs. It’s not a pretty sight. But it is an interesting one, especially to researchers.

Animal venoms are incredible compounds with remarkable properties—and many of them make excellent medicine. Many people with diabetes are already familiar with one of them; the drug exenatide was originally found in the spit of the venomous gila monster. Exenatide works by mimicking the behavior of an insulin-producing natural compound called Glucagon-like peptide 1 (GLP-1). The fact that the lizard has both venom and insulin-making genes is not a coincidence; many animal venoms, including the gila monster’s, induce low blood sugar in their prey in order to immobilize them.

It’s a good strategy with one flaw: GLP-1 and compounds like it break down and stop working very quickly, and people who have trouble making insulin really need their drug to keep working.

With this issue in mind, Australian researchers turned their attention to our duck-billed friends. They knew that platypuses, like people, made GLP-1 in their guts, and that platypuses, like gila monsters, make venom. The real question was how these two compounds interacted within a platypus’s body.

The researchers used chemical and genetic analysis to identify the chemical compounds in the guts and spurs of platypuses and in the guts of their cousins, the echidnas.

They found something entirely new: a tougher, more resilient GLP-1, one that breaks down differently—and more slowly—than the compounds in gila monster spit. The authors say this uber-compound is the result of a "tug of war" between GLP-1’s two uses in the gut and in venom.

"This is an amazing example of how millions of years of evolution can shape molecules and optimise their function," co-lead author Frank Gutzner of the University of Adelaide said in a statement.

"These findings have the potential to inform diabetes treatment, one of our greatest health challenges, although exactly how we can convert this finding into a treatment will need to be the subject of future research."


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