Octopuses Change Colors to Intimidate Their Foes, Study Finds

Octopuses are well-known for being anti-social, but new research is proving they aren’t as reclusive as scientists previously believed. In fact, their knack for changing their appearance—long thought of as an effective way to hide—may also be a way they communicate with other octopuses, a new study finds. Research from Alaska Pacific University and the University of Sydney published in Current Biology indicates that the ability to change the hue of their bodies plays an important role in conflicts between octopuses.

The researchers studied a species called Octopus tetricus by setting up cameras in the shallow waters of Jervis Bay off the eastern coast of Australia. In more than 50 hours of video, they catalogued 186 octopus interactions, noticing a pattern in the social lives of the eight-tentacled creatures: They tend to turn dark colors when they feel aggressive.

The octopus in the background of the photo is adopting an aggressive posture, while the pale octopus in the foreground is being submissive.

When a dark-colored octopus approached another dark-colored octopus, the two were more likely to fight, whereas if a light-colored octopus met a dark octopus, the paler of the two was likely to scuttle off in retreat. Dark octopuses were more likely to stand their ground during a beef, while lighter octopuses were more likely to beat it.

In addition to dimming the color of their bodies, aggressive octopuses typically stand up tall and spread their web out in a position "nicknamed the Nosferatu pose,” making themselves look as large and forbidding as possible, while submissive octopuses will slink down.

This adds to previous research that found that octopuses can be social in captivity, even cohabitating in dens. The authors of the current study suggest that octopuses may behave more socially in areas where there’s a lot of food to be had, but limited places to hide. The growing body of evidence for octopus interactions (that don’t involve eating each other) “indicates that we should no longer consider octopuses as solitary and asocial,” they write.

[h/t: NPR]

All images by David Scheel

Big Questions
What Makes a Cat's Tail Puff Up When It's Scared?

Cats wear their emotions on their tails, not their sleeves. They tap their fluffy rear appendages during relaxing naps, thrash them while tense, and hold them stiff and aloft when they’re feeling aggressive, among other behaviors. And in some scary situations (like, say, being surprised by a cucumber), a cat’s tail will actually expand, puffing up to nearly twice its volume as its owner hisses, arches its back, and flattens its ears. What does a super-sized tail signify, and how does it occur naturally without help from hairspray?

Cats with puffed tails are “basically trying to make themselves look as big as possible, and that’s because they detect a threat in the environment," Dr. Mikel Delgado, a certified cat behavior consultant who studied animal behavior and human-pet relationships as a PhD student at the University of California, Berkeley, tells Mental Floss. The “threat” in question can be as major as an approaching dog or as minor as an unexpected noise. Even if a cat isn't technically in any real danger, it's still biologically wired to spring to the offensive at a moment’s notice, as it's "not quite at the top of the food chain,” Delgado says. And a big tail is reflexive feline body language for “I’m big and scary, and you wouldn't want to mess with me,” she adds.

A cat’s tail puffs when muscles in its skin (where the hair base is) contract in response to hormone signals from the stress/fight or flight system, or sympathetic nervous system. Occasionally, the hairs on a cat’s back will also puff up along with the tail. That said, not all cats swell up when a startling situation strikes. “I’ve seen some cats that seem unflappable, and they never get poofed up,” Delgado says. “My cats get puffed up pretty easily.”

In addition to cats, other animals also experience piloerection, as this phenomenon is technically called. For example, “some birds puff up when they're encountering an enemy or a threat,” Delgado says. “I think it is a universal response among animals to try to get themselves out of a [potentially dangerous] situation. Really, the idea is that you don't have to fight because if you fight, you might lose an ear or you might get an injury that could be fatal. For most animals, they’re trying to figure out how to scare another animal off without actually going fisticuffs.” In other words, hiss softly, but carry a big tail.

10 Notable Gestation Periods in the Animal Kingdom

The gestation periods of the animal kingdom are varied and fascinating. Some clock in at just a few weeks, making any human green with envy, while others can last more than a year. Here are 10 notable gestation times for animals around the globe. The lesson? Be thankful that you’re not a pregnant elephant.

1. ELEPHANTS: 640-660 DAYS

Elephants are pregnant for a long time. Like really, really long. At an average of 95 weeks, the gestation period is more than double the length of a human pregnancy, so it shouldn't come as a shock that female elephants don't often have more than four offspring during their lifetimes. Who has the time?


A photo of a mother hippo and her baby in Uganda

Yes, it takes less time to make a hippopotamus than it takes to make a human.


Baby giraffes can weigh more than 150 pounds and can be around 6 feet tall. Another fascinating tidbit: giraffes give birth standing up, so it's pretty normal for a baby to fall 6 feet to the ground.


There’s a reason for the long wait: after that 17 months, Baby Shamu emerges weighing anywhere from 265 to 353 pounds and measuring about 8.5 feet long. Yikes.

5. OPOSSUM: 12-13 DAYS

A baby opossum wrapped up in a blanket

Blink and you'll miss it: This is the shortest gestation period of any mammal in North America. But since the lifespan of an opossum is only two to four years, it makes sense.


Hey, they get off pretty easy.


It's not a huge surprise that their gestational periods are pretty similar to ours, right?


A pair of black bear cubs

Also less than a human. Interestingly, cubs might only be 6 to 8 inches in length at birth and are completely hairless. 


This is the longest gestation period of any rodent. Thankfully for the mother, porcupine babies (a.k.a. porcupettes) are actually born with soft quills, and it's not until after birth that they harden up.


Baby walruses? Kind of adorable. They certainly take their sweet time coming out, though.


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