26 replies to this topic

[mistymani]

Oh red ah???? i have never seen such a octopus and it would have been nice shot..

[bvanant]

It was my understanding that each species will typically only possess three different colours of chromatophores and the patterns we see are based on different combinations of those chromatophores, similar to the way an RGB display works. The patterns are someone limited by the colours of the chromatophores and they can only make colours possible by the combinations.

As far as I know, fluorescent pigments are not known from cephalopods. The ones in cnidaria (corals, anemone, etc.) are proteins synthesised by the animals themselves and this is fairly unique to cnidaria. I don't believe algal symbiosis is known from cephalopods either - it is known from some gastropods which ingest cnidaria (hydroids and anemones) and steal their zooxanthellae.

The fluorescent alga idea is interesting, but I'm not sure how it could work.

The best way to see if it was fluorescent would be to photograph it using filters from NightSea. Basically you put one filter each strobe which only lets short wavelength through and another filter goes over the port and only lets light with longer wavelengths than what is blocked from the strobes. The only light that reaches the sensor/film will be fluorescence.

I have tried a couple of times to shoot octopi with a fluorescent setup and got mostly nothing but it is hard work since you need to have no lights going at all.
For a good review of pigments of a variety of sea beasties take a look at
http://pubs.rsc.org/...006/np/b307612c

Free content but you need to register. The authors suggest that some squid have fluorescent pigments but mention nothing about fluorescent octopuses.

Bill

[JamesWood]

Unfortunately the image links appear to be broken - I'd really like to see your images.

One thing I would be looking for is if the red color appears metallic. As far as I know, cephalopods are not fluorescent (absorbing one color of light and re emitting it as another) but are iridescent (differential refraction of light). The red anemone at 100 feet as well as the colors of many corals under uv light are great examples of fluorescence. The metallic color of many insects, especially certain metallic blue butterflies, is a good example of iridescence. Soap bubbles and oil on water are also examples. Iridescence is directional - change your viewing angle and the colors you see likely change. Color from pigments (most things) and from iridescence doesn't behave like that.

Cephalopods also have an iridescent system that is separate from their better studied chromatophore system. Unlike buttefly wings which are fixed, cephalopods can turn there iridescent system on an off!
Both iridescence and fluoresce can be very difficult to photograph. For iridescence you generally need to be shooting available light. What you see is not what you get when your strobes chance the angle and properties of the incoming light. For fluorescence, you may need to shot available light (its dim at 100 ft) or supply the “right” spectrum of light (often uv) and add a filter to your camera to block undesirable noise.

James B. Wood PhD
Wetpixel Science Moderator (who should check in more often!)
The Cephalopod Page Webmaster

[Tim Digger]

These two shots are I believe of the closely related mototie octopus. There was 21 secs between the shots and it changed faster than that when irritated by the dive guide. About 2-3 inches long delightful little beastie.
Tim Digger

[SimonSpear]

Wow didn't realise this was still being debated. I was actually going through my Blue Ring footage a week or so ago, so if I magically create some time this week then I can probably post a link to some example footage (if I can't do it this then it will probably be 3 more weeks before I can post it).

Cheers, Simon

[JamesWood]

These two shots are I believe of the closely related mototie octopus. There was 21 secs between the shots and it changed faster than that when irritated by the dive guide. About 2-3 inches long delightful little beastie.
Tim Digger

Nice picts Tim. The red and brown is the "normal" chromatophore system at work. As it is directly controlled from their brain, they can change colors in fractions of a second. The blue eye spot is from iridescence, a different system.

We sometimes see a similiar stripped pattern in swimming O. vulgaris (common octopus) in the Caribbean. I think it may mimic a local parrot fish.

James

[Caspir]

Nice shots, amazing work.