Where's The Octopus? (2011) [video] | Hacker News Reader

Where's The Octopus? (2011) [video]

sciencefriday.com

83 pointssethbannon20 comments

Growing up in a remote Australia desert beach, I spent a lot of time playing with creatures like this (among many others) and I have come to love them with a great deal of passion.

If you're ever in a situation where you want to play with an octopus, but are having a hard time getting its attention, remember this trick: take a gold coin out of your pocket, shine it in the sun, and use it to the lure the octopus into your domain. I've yet to meet an octopus I can't convince to play with me for a while, for the cost of an Australian gold coin or two.

Another thing that I love about these creatures is that they are intensely playful. I once watched an octopus playing with the sandfish around his hole .. he dangled an old crayfish head, long since hollowed out, at the end of a long string-like tentacle, luring the stupid little fish into his lair .. I watched him for hours, just lazily casting it out, bringing it back .. it didn't seem like he was fishing (although he'd have been quite capable of it) but more like just entertaining himself by watching the stupid little fish fall for the trick, over and over again ..

Lovely creatures. Be nice to them, you might make a reef friend. (Watch out for the blue-rings, though, you don't want to play with them too much, heh heh..)

While the video is amazing, the fact that statistical computer vision techniques aren't fooled in the least is astounding. It's not a purely visual trick, so much as a psychovisual one. Kind of like lossy compression of the surroundings.

It's also interesting how well the boundary is blended, as compared with other camouflaging animals.

The evolutionary pressure of "avoid being eaten" is enforced via the visual circuits of their predators, so it makes a certain amount of sense.

The narrator says that octopuses are colorblind and also says they use sight alone to camouflage based on their surroundings. How is one to reconcile these claims with the fact that the octopuses clearly take on the color of their surroundings when they camouflage?

It might not be a conscious decision for them. Their brain might automatically change their skin color to their surroundings, but that's a complete guess, I just can't imagine looking at something and "telling" my skin to change to that pattern and color.

This article suggests that octopuses see polarized light which might be one key to mimicking color. http://io9.com/5804055/squids-and-octopuses-imitate-color-de...

The narrator said the texture is matched by sight. It wasn't clear how the color is matched, though reflective skin spots were mentioned.

The narrator also said that how they did it was a mystery right now.

I got the impression that sight is used for textural changes but colour matching is via some other mechanism that isn't well understood.

There's a 3-video lecture on camouflage by Roger Hanlon (who took that video). The part about color-blindness is in part 2, here[1].

[1] http://www.youtube.com/watch?v=mtIiSXRv5no&t=33m23s

Thanks, that is a super interesting talk! He posits one mechanism for how the octopus might be able to colour-match while being colour-blind, which is the presence of distributed light sensing pigments in the skin - a molecule for this, "opsin", can be found in the skin of cuttlefish and squid (and maybe octopi too, he didn't say).

He says that although the pigment they have found for light-sensing is the same one they have found in the eye, and thus only indicates that the skin may be able to "see" a single colour (i.e. is also colour-blind), the research suggests that other pigments may exist, or that some other mechanism like refraction of nearby chromatophores (pigmented and/or light-reflecting cells) may allow those pigments to detect more than just a single colour.

When I was first trying to imagine how a colour-blind octopus could colour-match itself to its surroundings, one thought I had was how a deaf person can sense sound via felt vibrations. Based on the frequency of the vibration, pitch can be inferred. In a way, that is sort of similar to what he suggests is happening with the light-sensing pigments in the skin - the information the organism requires is fed to it via its skin rather than the organs typically used for this task, the eyes.

Wow, that old clip. I seem to recall that floating around the Internet even before the time of YouTube. Nice to finally see it in a decent resolution, though! ☺

Yes, but why on HN?

> On-Topic: Anything that good hackers would find interesting. That includes more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity.

I'm a hacker and rage comics gratify my intellectual curiosity. Now what? Pyrocat is right, deal with it. This kind of stuff has no place on HN.

Just out of interest, what stuff does have a place on HN? And why, specifically, should this not be on HN?

What part of "Science Friday" is not Hacker/Science-y enough?

The way the skin works is fascinating. I wonder if there's any potential for designing a display that works in a similar fashion :)

This is the video that put TED talks on the map

That talk http://www.ted.com/talks/david_gallo_shows_underwater_astoni...

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