Camouflage

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Either I broke the mouse or she thinks the water bottle is camouflage and we will never find her there. #mouse #ninja #camouflage

Octopuses may not be so antisocial after all!

Just when you thought octopuses couldn’t get any more fascinating, they do!

A paper published on January 28th, 2016 in the journal Current Biology found that there is more to octopuses changing colors than camouflage or anti-predator behavior. Using close to 53 hours of recorded video and 186 interactions in a heavily octopus-populated area in the waters of Australia, the scientists found that some displays of colors are signals that actually mediate combative interactions with one another. 

( Octopus in foreground turn pales when retreating from confrontation with another octopus, seen standing tall and menacing in the background. Photo by David Scheel)

This is the first study to document the use of signals during aggressive interactions among octopuses.

David Scheel recalls for NPR the first time he observed this behavior: “I took a look fairly early on at one sequence in which one octopus approaches another in a fairly menacing way. He gets all dark, stands up very tall, and the other octopus crouches down and turns very pale. And then, when the approaching octopus persists, the other one flees. And this is immediately followed by the first octopus approaching a third octopus that’s nearby. And the third octopus turns dark and doesn’t crouch down. He just stays where he is, holds his ground.”

Excerpts from the paper:

Interactions in which dark body color by an approaching octopus was matched by similar color in the reacting octopus were more likely to escalate to grappling. 

Darkness in an approaching octopus met by paler color in the reacting octopus accompanied retreat of the paler octopus. Octopuses also displayed on high ground and stood with spread web and elevated mantle, often producing these behaviors in combinations.

(Source: Scheel et al. 2016)

[An aggressive] octopus will turn very dark, stand in a way that accentuates its size and it will often seek to stand on a higher spot,” explained Professor Godfrey-Smith to the BBC.

The scientists in this research actually dubbed the pose “Nosferatu” because the spread of the octopus’s web was reminiscent of a vampire’s cape, and they looked like Dracula was approaching his prey.

In the end, the color displays ultimately are correlated with the outcome of the interaction. 

(Source: Scheel et al. 2016)

Scientists don’t exactly know why octopuses engaged in such heated and feisty exchanges. “It could be an attempt by one or more animals to control territory, as we saw males excluding males but not females, but this isn’t always the case,” Professor Godfrey-Smith said. 

It had been previously thought that octopuses were mostly solitary creatures, and changes to body color and shape were viewed as tactics to avoid predators or to hide. This study however not only shows a very interesting range of behavior, but also may indicate complex social signaling

Octopuses actually have a pretty exciting  and dramatic social life after all.

The video above shows a dark-colored octopus, standing in the Nosferatu pose before attacking another dark-colored octopus, which eventually turns white and retreats. 

You can find and download the full article on Current Biology.

Vertically camouflaged by the shape and color of the surrounding vegetation, a giraffe literally disappears in plain sight, illustrating the power of obliterative coloration to conceal an animal of any size. Each giraffe has its own unique markings made up of dark reddish to chestnut brown blotches of various shapes and sizes on a buff background. These patterns help them blend into a habitat of tree-dotted grasslands in South Africa’s Transvaal- by Art Wolfe 

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Here’s a mechanical chameleon!

Electronic engineers Guoping Wang, Xuechen Chen, Sheng Liu, Chingping Wong, and Sheng Chu have invented a mechanical chameleon which blends in real time with color backgrounds. The “chameleon” is a 3D-printed model covered in plasmonic displays.

They said in their paper: “The development of camouflage methods, often through a general resemblance to the background, has become a subject of intense research. However, an artificial, active camouflage that provides fast response to color change in the full-visible range for rapid background matching remains a daunting challenge.

To this end, we report a method, based on the combination of bimetallic nanodot arrays and electrochemical bias, to allow for plasmonic modulation. Importantly, our approach permits real-time light manipulation readily matchable to the color setting in a given environment.”

read more here and here 
Credit: ACS Nano (2016). DOI: 10.1021/acsnano.5b07472 

The Art of Camouflage

As Monty Python pointed out so wisely way back when, the objective of practicing this art is not to be seen (don’t hide behind a bush is my suggestion) and the wonderful named satanic leaf tailed gecko (aka Uroplastus (flat tail) phantasticus) is a master of the subject. As you can see from the photo it masquerades as a dead rotting and insect nibbled leaf, hanging off trees and branches awaiting unwary insects that might fly a little too close to its jumping tongue. It is endemic (ie only found in) to eastern Madagascan forests, where it lurks amongst the canopy, hunting at night.

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