The question of how octopuses can match their surroundings while not being able to see colours is one hell of a puzzle. Christopher Stubbs may finally have found the answer: chromatic aberration.
Maybe octopuses do see colour – not from light hitting special retinal “photoreceptors” but thanks to chromatic aberration, where different colours of light focus at different distances behind a lens.
Eyes of cephalopods are quite unlike anything seen on land: U- and W-shaped pupils backed by a lens that moves back and forth, like a camera, rather than fattening or thinning like ours. But they also have only one photoreceptor, unlike our red, green and blue ones.
Stubbs idea is the following: by adjusting the focal point of their eyes, like a photographer adjusts a lens, cephalopods might be able to detect different wavelengths – or colours – of light. This is called chromatic aberration.
To test his idea, Stubbs created a computer model of how the animals’ eyes work and see if chromatic aberration was possible.
He found not only could a shifting lens do the trick, but the cephalopods’ quirky pupils only served to maximise the effect. As Stubbs says, these creatures might exploit a ubiquitous source of image degradation in animal eyes, turning a bug into a feature.
The unusual pupils of cephalopods (from the top, a cuttlefish, squid and octopus) allow light into the eye from many directions, which spreads out the colors and [certainly] allows the creatures to determine color, even though they are technically colorblind.
As the lens moved forwards and backwards, the different wavelengths focusing on the retina at different times built up a colour picture.
It is not a proof, but the idea is definitely worth investigating !
New
research shows that human induced environmental changes to marine environments are leading to a
surge of cephalopods, the invertebrate group that includes octopuses,
squid, and cuttlefish.
Scientists have noticed a growth in cephalopod catches around the
world since the late 1990s. But drawing conclusions from national
fisheries data can be tricky. Not only can catch numbers be misreported,
but changes in catch amounts can also be influenced by factors that
change the amount of time people spend fishing—like the price of fish
and the cost of fuel—or by technological advances that allow fishers to
catch more.
So an increase in cephalopod catch doesn’t necessarily mean
there are more cephalopods in the ocean.
To solve this problem, researchers looked for data that would allow them
to calculate how much fishers catch over a given time period—a more
reliable metric of actual cephalopod population numbers…
Because of their adaptive abilities — rapid growth, short lifespans and flexible development — cephalopods are sometimes called “the weeds of the sea.” And it seems like that might be serving them well.
According to study published in Current Biology cephalopod abundance has increased since the 1950s. The reason for this growth is not yet clear, but it maybe that their adaptability has allowed them to thrive in a changing climate while other ocean dwelling populations suffer. Study author Bronwyn Gillanders says that figuring out the reason for cephalopod abundance may tell us a lot about “how human activities are changing the ocean.”
![0ct0pus:
“ Now you know.
[images and texts source]
”](https://66.media.tumblr.com/ad4771eb89b34dac73318a78649a2adf/tumblr_o8782n1aAE1v1xvwho3_500.png)
![0ct0pus:
“ Now you know.
[images and texts source]
”](https://66.media.tumblr.com/7add15779ebbe065b8b11978190e2fb0/tumblr_o8782n1aAE1v1xvwho2_500.png)
![0ct0pus:
“ Now you know.
[images and texts source]
”](https://66.media.tumblr.com/b212126e8c0fbe9dd79e14c2626a4e7c/tumblr_o8782n1aAE1v1xvwho4_500.png)
![0ct0pus:
“ Now you know.
[images and texts source]
”](https://66.media.tumblr.com/b4b641eb78c60b29cdc0bf31fc34deeb/tumblr_o8782n1aAE1v1xvwho1_500.png)
