

Where's The Octopus? (2011) [video] - sethbannon
http://www.sciencefriday.com/video/08/05/2011/where-s-the-octopus.html

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seclorum
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..)

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wffurr
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.

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

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sethbannon
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?

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kahirsch
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](http://www.youtube.com/watch?v=mtIiSXRv5no&t=33m23s)

~~~
adriand
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.

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teddyh
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! ☺

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pyrocat
Yes, but why on HN?

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DanBC
> 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.

~~~
throwaway391
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.

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

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

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SteveGuttenberg
This is the video that put TED talks on the map

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lechevalierd3on
That talk
[http://www.ted.com/talks/david_gallo_shows_underwater_astoni...](http://www.ted.com/talks/david_gallo_shows_underwater_astonishments.html)

