dear octopusexperts

i have been visiting this forum for a week now in search of ... well, let me explain my presence here first: i am currently doing research for a novel for kids, involving octopuses. it is going to be sheer fiction, but i do like to get facts right. And there are so many of them! not being a scientist in any way (not being a native English speaker also) I do admit i am getting lost in a maze of facts. My questions are very simple and presumably not interesting to people who know a lot. therefore i am seeking a kind knowledgeable person who can help me now and then. Anyhow, i'll be visiting this place regularly to pick up information, but it would be great to have someone in this huge aquarium to refer to in times of need.

thanks

Anna

:welcome:

well youve come to the right place! :smile: most everyone here can help you out, or knows someone who can.

Ask Jean. Jean knows everything lol. :)

We actually have a number of authors on this site, and they will always bend out of their way to help out !

Welcome!

Greg

:welcome: I think you can relax, we get a lot of people for whom English isn't a first language (and a lot of native speakers who seem to have even more trouble with it :tongue:) and we're very much used to questions that run the spectrum from "completely naive" to "you need a PhD to be able to understand the question well enough to say you don't know." I'm sure you'll find people happy to help you without being an imposition...

thanks

i'll probably end up bothering one of you three (or all of you three) with silly questions like: (to give a taste of what is to come:) is it true that an octopus with more than 90 arms has once been found?
what is btw the best way to get my questions answered? Can i post them publicly? Though they are going to be silly... or can i write private messages to any of you?

You can write private messages, but I believe posting them publicly is a better idea. You will get answers from the whole community.

hmm, this is going to be a strange new experience...

thanks in advance for wanting to help out

already feeling a little less lost

i wasn't joking about that 90-armed octo btw...think such a species really existed?

There have been a couple of octos documented with arm tips branching out of the 8 primary arms. They're not a distinct species, just a random (but fascinating) mutation.

thanks

i'll probably end up bothering one of you three (or all of you three) with silly questions like: (to give a taste of what is to come:) is it true that an octopus with more than 90 arms has once been found?
what is btw the best way to get my questions answered? Can i post them publicly? Though they are going to be silly... or can i write private messages to any of you?

I'm with Lime on this, posting them publicly will be both more fun, and get a wider range of answers, and have a lot of eyes checking them for validity.

As far as "90-arms" go, the only living cephalopod that naturally has 90 or so arms is the Nautilus, the last of the shelled cephalopod lineage. No one really knows how many arms the ancient nautiloids and ammonoids had, but there's some suspicion that the ammonoids probably had ten arms... squids, octos, cuttles, and the weird outlier Vampyroteuthis are all based on the ten-arm pattern (octos have lost a pair, but there's some evidence that they once had them.)

There is, though, an unusual mutation of octopuses where the arms branch, see http://www.tonmo.com/forums/showthread.php?t=2109

(there's another pic somewhere, too.) Also, some 9-armed octo was in the news recently, but it was in a sushi restaurant in Japan IIRC, so it wasn't studied scientifically. I suspect extra arms in cephs are a somewhat common developmental effect, like cats with extra toes.

:welcome: Hope we can help you!

If you can give an idea of what you want to say in your story (the factual part) and an idea of how it fits with the fantacy, it might help with the answers. Using this single thread for your questions (not posting a new one with each question) might also be helpful when you need to review as well as keeping the ideas in context. Some of us are over enthusiastic when it comes to books about octopuses and their cousins (fiction or non-fiction) so you should get a nice range of replies and some interesting discussion. Please also post when the book publishes as there is likely a native speaker in the crowd.

thanks everyone, this is really fun

i'll stick to this thread then for the time being

however, i cannot for the life of me tell you all what i am writing about, i have always been very very superstitious when it comes to books still being written, so it was a huge step already to come to this forum and start asking questions "in public". As soon as it is born (the book), i'll make up for that. but knowing me, it might still take at least a year or more...

here's one q that's been bothering me for a while: why keep octopuses as pets?


thanks again

anna

An answer from a non-keeper may be less insightful, but I would like to give it a go, regardless...

Octopuses fascinate us because they are fundamentally different from what we've come to expect as "normal". From a biology standpoint (copper rather than iron as oxygen carrier, no internal skeleton, living underwater etc.) as well as from behaviour: The octopus is a solitary animal that regardless of that fact posesses defined social skills: they interact rather enthusiastically with their tank-owners (no one owns another creature's life) and have a certain degree of recognizeable intelligence, as in memory skills and problem solving abilities. I also think that the two eyes in combination with the bulging mantle give off the impression of a human head of sorts, making the actual differences in ontogeny even more striking.

I have been wondering too about this "copper as oxygen carrier". Are octo's the only animals with blue blood or are there others? and why blue? why exactly copper? i read that it made them tire out more easily and that they "used" copper because it is found at the bottom of the ocean. does this make sense at all?

Your question makes perfect sense... here is my stab at answering it:

Octopuses are one of many organisms that use copper-based blood (the molecule containing the copper is called Hemocyanin, analogous to hemoglobin in humans and other vertebrates, which contains iron). Essentially all other mollusks have copper-based blood as well (with a few odd-balls using iron-based blood, mostly hydrothermal vent critters), as well as arthropods (insects, spiders, crustaceans like crabs and lobsters) and some various worms. Really there are probably more species on earth today that have copper-based blood than iron-based.

Why octopuses use hemocyanin (copper-based blood) rather than iron-based blood is a really big question that is very hard to answer simply. The best reason is probably because their ancestors did (other mollusks). But using copper based blood gives them a couple of advantages, one of which being that it can work better when the octopus is in low oxygen environments.

Why is there blood blue? Well that is because copper is blue in the particular oxidation state (fancy phrase meaning how it is bonded to other things) of which octopus blood uses it to carry oxygen. Metals turn different colors depending on how they are bonded to other chemicals, like oxygen. Fort instance pennies appear the familiar "copper" color, because they are bound to a lot of other copper molecules. The Statue of Liberty, however, looks green, because the copper it is made of has "rusted" and bound to oxygen. The copper in octopus blood is bound to both a blood molecule (the hemocyanin) and an oxygen molecule, so it turns blue. You can see the same thing in your blood, with the iron in it. When the iron in your blood is bound to both oxygen and hemoglobin, it is red, but when the iron is not bound to the oxygen anymore (in your veins) it is blue. You may be interested to know that octopus blood when there is no oxygen in it (so when it is in the veins instead of arteries) is actually clear, and not blue.

As for octopuses getting tired out more easily because of using copper-based blood, this is really blown out of proportion by most people. This is very true for a lot of other organisms that use copper blood (like crabs and such...) but octopuses and squid are such high performance animals (especially for invertebrates), that they have overcome more other the limitations of copper-based blood, and really it has performance comparable to some fishes.

Ok, that is a very long response to all of that... if there is anything you don't understand, let me know and I explain it another way, or if you want to know anything else... just holler.

Taollan said a lot there (:notworth:) but I'd add a couple of other details, just 'cuz:

I doubt there's much more copper at the bottom of the ocean than iron. Something I've always found a bit peculiar is that octopuses, and many other invertebrates with copper-based blood, find very small concentrations of copper toxic. So it's an element that's vital for their survival, but they can't stand it. Of course, nitric oxide and chlorine are similar for humans: they're important for us to live but toxic when we breathe them.

In both hemocyanin (sometimes spelled haemocyanin, for extra confusion) as in hemoglobin (haemoglobin) most of the molecule is a big structure made of the usual protein components, and there is just a big metal ion smack in the middle, that is very good at binding to oxygen-- in a probably-oversimplified example, a bar of iron will oxidize into rust, just as a bar of copper will oxidize into "verdigris." (confession: I don't know how much the fact that pure metals are easily oxidized is related to is use binding oxygen in blood... one difference is that in blood, the process is easily reversible, while you can't really "un-rust" metal easily.)

Understanding "why copper" may often be a historical coincidence, too: some early organisms developed hemocyanin as an oxygen transporter, which gave it a huge advantage over something that didn't have it, and others developed hemoglobin, which also gave an advantage over just using oxygen dissolved in seawater or similar. Both types of animals could be more active, and larger, but there's no easy path for an animal of one ancestry to lose one of these transporters and gain the other (although, to be fair, a few molluscs have done that, apparently... I wonder if anyone knows the mechanism... transgenic / horizontal gene transfer? retrovirus? mutation?)

Evolutionary genetics has a notion of "strongly conserved" characteristics, and in this case, the ability to efficiently transport oxygen is so vital to the survival of these animals that most changes away from their favored blood "pigment" are very much selected against, even if there is a "better" pigment that would work for... Evolution is usually about adaptation to "nearby" characteristics, and while the more radical changes make a bigger impression, they're not really the bulk of changes, and happen much more often in mass extinctions followed by species radiations. In the case of blood pigments, one might hypothesize that in a low-oxygen period, any animal that didn't have really good oxygen transport died out, and perhaps hemocyanin and hemoglobin were the only "good enough" systems for active animals, and after the oxygen came back, those two groups "radiated" with relatively small changes to take over all of the niches left when animals that used other pigments died out. Sometimes, the importance of a something in ancient history gets "locked in" as well: because the blood pigment was so important millions of years ago, now animals have very efficient systems and can be very wasteful of oxygen, by being active, smart, fast predators like cats, or fast and active fliers like hummingbirds, or cerebral big-brained primates like us. But in the current world, any species that doesn't have a good oxygen transport system is at a severe disadvantage compared to the ones who ran the gauntlet millions of years back, so any changes that move away from the "good" system are liable to make things worse before they make things better.

Is there another know oxygen carrier today besides hemocyanin and hemoglobin? If so what creatures use it?

Why keep a octopus? I can't give you an answer but I will throw out some ideas that might weave their way into your imagination.

From my observations of people looking at my various marine tanks, there are some people that have an immediate negative reaction the first time they see an octopus. You can almost see shivers and the reaction is much like people that are terrified of spiders or snakes (people terrified of spiders do not necessarily translate that to octos though, even with the eight arm similarity) . Then there are people like those who dwell here and the first reaction is total facination. I am not sure what makes the reaction so opposite. I can suggest that is it not familiarity with the ocean, however, as the diver/collector that caught my favorite pet was very much afraid of him and another diver/collector I know cannot understand why anyone would want to keep one. Fishermen consider them a nuisance and/or bait. The wife of the first (not a diver), however, was infatuated when Lynn caught and brought Octane home. My 9 year old granddaughter enjoys watching and feeding them and finally decided she wanted to pet mine, her teachers don't believe her, even with pictures (however, this was true of seahorses as well and they don't tend to have the negative reaction observed with the octo). Some people will describe them as "slimy" other as "soft" I would use "cuddly" but I don't think many others would agree to that adjective - but then again, we are seeing more and more stuffed animals and baby toys depicting friendly octos. Perhaps it has something to do with a Doctor Do Little syndrome and a wish by some people to have the ability to communicate with animals while others find the idea absurd.

Is there another know oxygen carrier today besides hemocyanin and hemoglobin? If so what creatures use it?

I don't know if this counts, but some animals don't have special carrier molecules, and use seawater, and I think some use other fluids (including sap, in plants, perhaps) or just diffusion of oxygen through tissues.

I'm pretty sure starfish and other echinoderms just use seawater to get oxygen around. Sponges even more so... I think starfish do some active pumping, while sponges use little cillia (moving hairs) to move fresh, oxygenated water around.

I don't know if there are any animals with closed circulatory systems that use dissolved oxygen but don't have a carrier molecule that's hemoglobin or hemocyanin, but I think some don't have special cells like our red blood cells, and even if there aren't any now, it seems likely that animals developed a closed circulatory system first (probably in the Cambrian or earlier) in order to become larger and bring oxygen to the parts far from the outside, and then carriers were an improvement on that model. Worms frequently survive as the last of such animals, so I wouldn't be shocked to find some surviving worm that still works that way.

I looked up velvet worms, since they're often interestingly weird, and found that

Internally, velvet worms have a tube-shaped heart that pumps blood through an open circulatory system. The blood, however, does not carry oxygen. Instead, oxygen is brought in through minute trachea located all over the surface of the skin. The openings to these trachea are sites of major water loss, but similarly can easily cause the drowning of a velvet worm. Thus, the phylum Onychophora is the only phylum in which none of its living members are aquatic. (from http://www.angelfire.com/mo2/animals1/phylum/velvetworm.html )

This is, in fact, nice and weird, particularly since their ancestor Hallucigenia was aquatic so presumably didn't have the drowning problem. Exactly what the blood is used for if it isn't respiration isn't clear, perhaps just for getting nutrients to the cells and waste (maybe including CO2) away from them? But it doesn't answer your question :rolleyes:

this is all amazingly mindbogglingly interesting though it might take me some time to digest all...so i'll just quietly chew on this all day (all night for most of you on the forum :)

thanks!

anna

Is there another know oxygen carrier today besides hemocyanin and hemoglobin? If so what creatures use it?


Hemerythin: it is another iron containing O2 transporter but lack a Heme group that defines Hemoglobin and Hemocyanin. Sipunculids and Brachiopods use this transporter

Vanabins: These are metalloproteins that bind vanadium (strange, strange:bonk::cyclops:) and are used as blood O2 transporters by Tunicates.

I can't think of any others right off, but I will let you know if I come up with some.

Hemerythin: it is another iron containing O2 transporter but lack a Heme group that defines Hemoglobin and Hemocyanin. Sipunculids and Brachiopods use this transporter

Vanabins: These are metalloproteins that bind vanadium (strange, strange:bonk::cyclops:) and are used as blood O2 transporters by Tunicates.

I can't think of any others right off, but I will let you know if I come up with some.

Ah, delightfully good esoteric information :notworth: :grad:

Is there a good reference for "comparative oxygen transport systems" across the Animal kingdom, or is this the sort of stuff you have to pick up on the street? I utterly failed to find the right google terms to find such a thing, and while there are some good refs in books I have about lung/gill anatomy and such for oxygen uptake, I found almost nothing about how it gets moved around after it's in the body.

a down to earth question arises in my simple mind...i somehow thought that the elements in the blood of living creatures is due to what they take in as food, so a copperblooded creature would need to take in some copper to stay healthy, whereas we ironblooded ones need some iron to survive (like when you've donated blood, sometimes you're given iron pills to strenghten yourself) so it would be logical that creatures are either hemoglobinous or hemocyaninous depending on what element is most available in their surroundings

sincerely hoping this question will not be provoking roars of disdainful laughter, i remain, etc

your interested pupil :snorkel:

'fraid not, even small traces of copper are deadly to an octopus and is the first mentioned problem with purchasing a used siliconed sealed tank that may have been treated with a copper medication.

Back in 2000, Heinz Decker and Nora Terwilliger published a good paper on the evolution of copperbased oxygen carrier molecules:

COPS AND ROBBERS: PUTATIVE EVOLUTION OF COPPER OXYGEN-BINDING PROTEINS (http://jeb.biologists.org/cgi/reprint/203/12/1777.pdf)
The Journal of Experimental Biology 203, 1777–1782 (2000)

©The Company of Biologists Limited 2000

The grounds for it being utilized by cephalopods in preference to iron, is likely that it works well based on its physical properties in an oxygen scavenger molecule, and certainly well enough to survive the competition and get awarded evolutionary success as a carrier in a circulatory system. Again, as the case was made earlier in this thread by Monty, once you (as a lineage) invest energy in a certain route of evolution for one of your basic requirements, it is nigh to impossible to reverse and go an alternative route altogether; think composite eyes, for instance, or arthropod trachea versus a proper respiratory system.

:confused:

be patient with me, all of you, if i keep on asking what seems the same question over and over again:

this copper-in-blood-issue: discussing this over dinner just now (yes, well, obsessed writers tend to involve their whole family) with my husband, he kept on wondering where the copper in the blood then did come from, if not from food and why it was so poisonous, and yes, common reason says it doesn't make sense that you die from what you need to survive. do other "copper-in-blood animals" have this huge allergy to copper as well?

An element in one form can have totally different physiological effects than in another form. Lets use a human example: Chlorine. You absolutely need chlorine to survive. If we were somehow able to take every last chlorine molecule out of your body, you would die instantly. You normally get chlorine in the form of sale (NaCl, sodium chloride). When salt is dissolved into solution in water, the chlorine molecule separates from the sodium molecule and is just the negatively charge ion, Cl-. This ion is what your body will take up and use.
If the chlorine is in the "elemental" form, bound to another chlorine (Cl2) it is usually a gas and is very toxic to humans.
OK, with all that being said, that is how you can have something you need also be toxic. As for where octopuses get their copper from, most of their food items (Clams, snails, crabs), also have copper based blood, and I would image provides them with ample copper for their own blood, in a safe form already bound to the hemocyanin.

thanks, very clear now!!! will explain to my kids at bedtime :hmm:
it is just that it seems not such a good idea for an octopus to be so queezy about just a little copper, something which i can imagine is easily found anywhere

do the other copperbound animals (spiders, crabs, etc if i'm not mistaken) have this problem as well?

Is there a good reference for "comparative oxygen transport systems" across the Animal kingdom, or is this the sort of stuff you have to pick up on the street?

I don't know of one right off. I was slow in answering because I was poking around. I mean there is a lot of stuff out there looking at Hemoglobin and hemocyanin comparisons, sometimes even grabbing Hemerythins, but I don't know of anything right off that is global. My best reference for some of these is "Invertebrates" by Brusca, which was my Ad. Marine Inverts class text in my master's program. I think it has everything I mentioned in it. (Verts are boring... I think they all only use hemoglobin)

P.S. I have one more for you, that I shouldn't have forgotten. Chlorocruorin, which is another iron-porphyrin ring repiratory pigment used by some annelids.

do the other copperbound animals (spiders, crabs, etc if i'm not mistaken) have this problem as well?

I am not quite sure what all animal have copper toxicity issues, but a lot of invertebrates do. I know most gastropods and bivalves have problems with copper, but I am not sure about crabs. I don't believe that the copper being toxic is directly related to copper being in their blood, so one can't assume copper in blood = copper toxic.

OK, with all that being said, that is how you can have something you need also be toxic. As for where octopuses get their copper from, most of their food items (Clams, snails, crabs), also have copper based blood, and I would image provides them with ample copper for their own blood, in a safe form already bound to the hemocyanin.

I've heard that copper can also be toxic to other molluscs, though, so this just pushes back the question to "how do filter feeders and algae eaters like clams and snails get their copper?" I'd guess that they have some mechanism to extract it from the environment while avoiding toxicity, so presumably there is a "too little copper" as well as "too much copper" problem. As you say, though, it could also be the chemical form that the copper is in, somehow...

When hypothesizing about things like iron vs. copper levels in the environment, it's important to keep in mind that these blood pigments have been around for a very long time-- you can tell by looking at the differences in the proteins and genes that encode them in different species, and since we know from the fossil record that arthropods diverged from molluscs well before the cambrian, yet both have hemocyanin that shares enough characteristics that it couldn't have arisen separately, so hemocyanin evolved well before the Cambrian, which was a very, very long time ago. The atmosphere, oceans, temperature, other life forms, volcanism, and other geology of the earth were very different... so even if hemocyanin developed at a time when there was a lot of copper in the water for some reason, those conditions were at the time some early worm-creature first used it, say, to be able to out-compete other worms in some "eating bacterial mats or Ediacaran/Vendian critters" environment, or just to grow bigger in low-oxygen environment, so applying them to the modern creatures that use this pigment doesn't take the tremendous changes in the environment into account.

Perhaps a restatement of the question is "are there factors in having hemocyanin as a blood pigment that make it harder for those animals to compete in certain niches or environments?" or even "is there a pattern as to where hemocyanin-using animals get their copper, or do they show a number of diverse adaptations to get it?" and "how can we compare and contrast the similarities (convergent evolution) and differences (evolutionary diversity) that we see in the copper-using and iron-using animals, and learn anything interesting?"

This isn't to say that it's bad to ask the question of "how to the animals who live in a particular environment both take advantage of the resources and adapt to the constraints of the environment," I just think that because of the very long time-scale stability of the blood pigments that the particular pigment any animal uses is far more dependent on its ancestry than it's current environment. That can probably be decoupled, though, from the question of how the animals get the raw materials (e.g. copper, iron) to manufacture their blood pigments.

Here's an interesting twist to that: there are a lot of midwater squid that primarily feed on fish, right? Fish use hemoglobin, and probably don't have a lot of copper, and the squid have a very rapid growth rate, and so must add to their blood volume rapidly. They are cannibalistic to some extent, but there must be some other copper input to the system for the shoal of squid to ever grow in mass... perhaps that's part of the story where the Humboldts were filmed scooping up krill. Implications of this for researchers feeding their laboratory squids a diet consisting only of fish is left as an exercise for the reader.

I am not quite sure what all animal have copper toxicity issues, but a lot of invertebrates do. I know most gastropods and bivalves have problems with copper, but I am not sure about crabs. I don't believe that the copper being toxic is directly related to copper being in their blood, so one can't assume copper in blood = copper toxic.

Yeah, I've spent a fair bit of time on google scholar trying to find references on what exactly it is about copper that causes problems for invertebrates, and what form that copper must be in to be problematic. I guess I haven't really gone the other way, and found out what form it's in in the medications that frequently cause problems in tanks.

I would expect in seawater that the majority is ionic copper, extrapolating from NaCl dissolving into Na+ and Cl- I would think cupric chloride would go to Cu2+ and 2Cl- or something like that, but wikipedia says that makes me really naive (http://en.wikipedia.org/wiki/Copper(II)_chloride)

p.s. a little further reading suggests that the Ich treatments are copper sulphate. The wikipedia page http://en.wikipedia.org/wiki/Copper_sulfate suggests that copper ions that result from that are toxic to fish, so care is needed not to overtreat. This is also an interesting reference on treating Ich: http://edis.ifas.ufl.edu/FA006

To extend our naivety, would it be viable to suggest that the need for copper to increase blood volume be a partial reason cephs need a higher salt content than most other reef critters?

To extend our naivety, would it be viable to suggest that the need for copper to increase blood volume be a partial reason cephs need a higher salt content than most other reef critters?

Er, I'm not really clear what you mean... table salt is NaCl, so no copper is in it.

Apparently, "Standard Seawater" (per http://www.geochemie.uni-bremen.de/koelling/standards_seawater.html ) has a bit of copper, but the "Artificial Seawater" variant described on wikipedia at http://en.wikipedia.org/wiki/Artificial_seawater has none. See also at http://en.wikipedia.org/wiki/Seawater

They certainly can't make copper from salt water alone (NaCl in H2O) without nuclear fusion. Not that I have anything against cephalopods with nuclear fusion capabilities.

Certainly, since there are land-based and freshwater critters with hemocyanin, being in salt water isn't a general requirement... in fact, freshwater and land molluscs don't enjoy salt much at all...

I had forgotten that copper is one of the things intentionally excluded from the artificial sea water salt mixes. To be honest I grasp at a lot of straws to try to explain why my tank reared mercs were half the size of the WC mom and the tank bred were half the size of the tank reared (Wiley, my last of Trapper's line is tiny and getting to be an old man). Quantity of food available does not explain it and I am kind of alone in the hobby world with this experience. I keep hoping others will continue a line of cuttle or octo to see if this is typical of something I am not providing.

Not that I have anything against cephalopods with nuclear fusion capabilities.

I, for one, welcome our squid overlords :wink:

dear friends

as this discussion continues, i feel the urge to write a horror novel with mad nuclear octopus scientists ready to destroy the world for want of a bite of good copper, should make a best-seller, especially if i include these hair-raising conversations...

I, for one, welcome our squid overlords :wink:

We are here. Bow down.

Don't mock me, I've seen what even their most docile blobs can throw at us, this is no time for dilettant humour! Next thing you'll know you'll be humming along to Sweet Caroline...

i have a completely new question: i have been surfing around for information for weeks now and i seem to find contradictory information about the difference between squid and octopus: squids have inner shell, octopuses don't, squids have two extra tentacles, but some say the only difference is in the suckers, squids have hooks on them ??? when i look at photo's it seems indeed difficult to see the difference between some octopuses and some squids. how could one explain this Very Simply?

Octopus have 8 tentacles (arms), while squid have ten. With a squid, two of those are used as grasping arms for catching fast moving prey, and many species have sucker disks with hooks.

If you see video of a squid hunting versus an octo, you will understand quickly. Octopus typically hunt by ambush, sneaking up on the prey item, whereas squid chase down their food by using pure speed.

Many of the cephalopods have a "cuttlebone" that varies in size from species to species. In some, it is as thin as a piece of packaging plastic, and in others it is thick enough to warrant saving for parrot chews. Sigh.

Sorry before-hand for the horrible formatting:

"An interesting element in cephalopods is Cu. Thismetal
is required in large concentrations in cephalopods as it
works as a respiratory pigment in hemocyanin which
represents 98% of their blood proteins (Ghiretti, 1966;
D'Aniello et al., 1986). From the literature, levels of Cu are
reported for the gills, branchial hearts, digestive gland and
muscle of adult cephalopods, including O. vulgaris (for
recent literature review see Table 6 of Napoleao et al.,
2005a). The Cu concentrations observed here in O.
vulgaris hatchlings are similar to that reported for the
gills of adults of the same species. The Cu abundance in the
adult octopus gills may reflect the presence of haemocyanin,
the dioxygen carrier Cu protein typical ofmolluscs and
crustaceans (Taylor and Anstiss, 1999). However, these
levels of Cu for the octopus hatchling, as a whole animal,
seem to be relatively high compared to the adults. The
richness in Cu of planktonic octopus may indicate a
particular high nutritional requirement for this element. In
decapod crustaceans, enzymatic requirements have been
estimated to be around 26 μg g−1 of Cu and the total
metabolic requirements (enzymes and haemocyanin) to be
around 83 μg g−1 (Rainbow, 1988; Zauke and Petri, 1993).
These estimated requirements for adult octopus are similar,
reaching levels of 26 and 92 μg g−1 of Cu, respectively
(White and Rainbow, 1985). Crustaceans constitute the
main prey of many cephalopod species, particularly during
paralarval and juvenile stages (Vecchione, 1991; Passarella
and Hopkins, 1991) and crabs are the preferred prey of
adult octopus in the wild (Nixon, 1987), between other
reasons, probably because they are rich in Cu, Zn,
cholesterol and n-3 fatty acids (King et al., 1990; Skonberg
and Perkins, 2002). García García and Cerezo Valverde
(2006) reported the optimal proportion of crabs in a fish
+crab diet for ongrowing subadult O. vulgaris, noted that
no cannibalism are reported when the minimum levels of
crabs are maintained in the diet and pointed out a possible
Cu dietary influence. In the same way, mortality associated
with low Cu content diets has been also signalled for
subadult cuttlefish S. officinalis (Castro et al., 1993).
The present results seems to confirm the importance of
the Cu in the diet of O. vulgaris as 1) paralarvae of 20 d
old feed on an Artemia diet showed significantly less Cu
content that the “natural” Cu profile of hatchlings or wild
juveniles, and 2) the paralarval group with poor survival
(control) recorded the lower Cu content in comparison
with the higher levels recorded for the group with best
survival. In addition, prey composition analyzed here
showed that Artemia nauplii have Cu levels 20 times
lower that O. vulgaris hatchlings and 8 times lower that
M. brachydactyla zoeae, a prey used previously with
success as food for rearing O. vulgaris paralarvae
(Carrasco et al., 2003; Iglesias et al., 2004). The low levels in Cu of the reared O. vulgaris paralarvae feeding
on Artemia nauplii may suggest that they are resulting
from the low Cu content of Artemia and/or resulting from
the poor physiological stage of the octopus paralarvae.
Conclusions on this subject need further research,
however, the Cu content of the M. brachydactyla zoeae
(73 μg g−1, see Table 5) may be considered as an optimal
estimation of the Cu feeding requirement for O. vulgaris
paralarvae under culture conditions. The deficient nutrient
composition of Artemia as the sole larval food for O.
vulgaris paralarvae is well known, particularly for lipid
requirements (Navarro and Villanueva, 2000, 2003;
Villanueva et al., 2002). However, in addition to other
nutritional requirements, mainly from lipidic origin, Cu
seems to be an important element on the paralarval octopus
diet. Future studies are necessary to quantify these
Cu dietary needsmay testing a possible lipid+bioavailable
Cu enriched Artemia suitable for paralarval octopus culture.
To this respect, it should be borne in mind that Cu
uptake by Artemia is influenced by pH and temperature
(Blust et al., 1988, 1994)."
From:
Villanueva, R. and Bustamante, B (2006) Composition in essential and non-essential elements of early stages of cephalopods and dietary effects on the elemental profiles of Octopus vulgaris paralarvae. Aquaculture 261:225-240

A popular misconception is that squid have eight arms and two long tentacles, while octopus have eight arms and no tentacles. But this is not always the case. The only real difference between the two groups is that squid have hooked or saw-like suckers, and octopus do not

http://www.teara.govt.nz/EarthSeaAndSky/SeaLife/OctopusAndSquid/1/en

http://www.teara.govt.nz/EarthSeaAndSky/SeaLife/OctopusAndSquid/1/en

I am going to have to respectfully disagree with the website you quoted. The presences of two tentacle in addition to eight arms is the fundamental difference between octopuses and squid. Yes Some squid seem to only have eight arms (Family octopoteuthidae) But even in those squid I believe you can detect extremely reduced tentacles or you can tell they lose them during development

I can't think of a particular squid that lacks sucker hooks and sucker rings, but lets consider this:
if a cephalopod was discovered today that has no sucker hooks or rings, but did have eight arms and two tentacles, the information from the above link would suggest that such an animal would be considered and octopus. I would contend it would be instead a squid (or cuttlefish or other decapodaform).

I am going to go further and disrespectfully disagree. The web site is just wrong.

There are a number of other, more subtle morphological differences as well, and the taxonomy is largely agreed at the level of the difference between squid, octopus, cuttlefish, and vampyroteuthis. I'm a bit skeptical about spirula, but even there, it's clear that it's in the squids and cuttles department.

A good reference is tolweb, compare the squids and cuttles http://www.tolweb.org/Decapodiformes/19404 to octopods and vampire squids http://www.tolweb.org/Octopodiformes/19405 to get the full list of officially recognized distinguishing characteristics.

I found this (http://www.saltinstitute.org/47o.html#) about farm mammals while looking for some hints on copper absorption for young octos and found it interesting that copper is high in young mammals too. Since much does not translate between cephalopods and mammals it would be hard to have much take away from the info provided but it was interesting that increasing calcium lowered the toxicity of copper in the diet. I sure wish one of our grad/post grad students would study and report on octo nutrition, poking about by an illiterate hobbiest approaches futility.

I did find this article (http://www.copper.org/publications/newsletters/innovations/1998/12/water_health.html), translated into non-scienctific lingo that has me thinking about a non attached refugium ...

Although requirements have not been determined for every marine species, scientists do know that copper deficiencies in certain species can result in reduced growth and cataracts, among other symptoms. Conversely, scientists have observed that overly high presence of copper in natural waters, due to pollutants or produced experimentally, may badly damage gills, adversely affect the liver and kidneys of fish or cause some neurological damage."

Scientists are frequently frustrated in their efforts to study more closely the effects of too little or too much copper on aquatic species in the wild because it is unusual to find whole fish that have died slowly as a result of malnutrition. "In the wild animals with deficiencies get quickly eaten or decompose," says Dr. Shearer.

thanks for the corrections about the difference btw octopus and squid and the links

somewhere else on this wild wild web i read that the colour change in octopuses was also a way to show emotion: red for being angry, etc...sounds like far-fetched "humanising", no?

Not really; the colour changes are consistent with behaviour, so they must be corellated. White is for instance associated with a startle reflex, a pounce will bring out dark contrasts. Some squid will even use wavey patterns to signal the intention of courtship to a potential partner on the side of their mantle visible to said other squid, while flashing white on the "invisible" side to ward off fellow suitors! In fact, if the relative visual positions change, the male squid will actually inverse that scheme and make it change sides... Octopodes (yes, I am pedantic :wink:) will even change the texture of their skin to match their mood or surroundings. Do they have moods? Disregarding a fair share of anthropomorphism, most people taking care of one will agree they do.

I think a lot depends on how you define "mood" or "emotion". In my understanding of neural networks (the real ones, consisting of neurons), these are elements of consciousness that arise early in evolution. PET scans in humans for instance show some very basic emotions to be stemming from the amygdala, a fairly ancient and primitive part of our brains. Reptiles have it, even fish sort of have it, so why not the physiological traits to go with it? My guess is, that given the complexity of the octopus brain, they stand a fair chance of having benefitted from having an emotional foundation to underpin their behaviour. Whether an octopus interprets emotion, is obviously a wholly different matter.

Octopodes (yes, I am pedantic )

kind sir, please do explain to this ignorant bipode the exact meaning of this remark

Pardon my Greek.... This stems from a longstanding discussion on this forum. I'll explain by quoting the Wikipedia:

There are three forms of the plural of octopus; namely, octopuses, octopi, and octopodes. Currently, octopuses is the most common form in the UK as well as the US; octopodes is rare, and octopi is often objected to.[19]

The Oxford English Dictionary (2004 update[20]) lists octopuses, octopi and octopodes (in that order); it labels octopodes "rare", and notes that octopi derives from the mistaken assumption that octōpūs is a second declension Latin noun, which it is not. Rather, it is (Latinized) Greek, from oktṓpous (ὀκτώπους), gender masculine, whose plural is oktṓpodes (ὀκτώποδες). If the word were native to Latin, it would be octōpēs ('eight-foot') and the plural octōpedes, analogous to centipedes and mīllipedes, as the plural form of pēs ('foot') is pedes. In modern, informal Greek, it is called khtapódi (χταπόδι), gender neuter, with plural form khtapódia (χταπόδια).

Chambers 21st Century Dictionary[21] and the Compact Oxford Dictionary[22] list only octopuses, although the latter notes that octopodes is "still occasionally used"; the British National Corpus has 29 instances of octopuses, 11 of octopi and 4 of octopodes. Merriam-Webster 11th Collegiate Dictionary lists octopuses and octopi, in that order; Webster's New World College Dictionary lists octopuses, octopi and octopodes (in that order).

Fowler's Modern English Usage states that "the only acceptable plural in English is octopuses," and that octopi is misconceived and octopodes pedantic.

The term octopod (plural octopods or octopodes) is taken from the taxonomic order Octopoda but has no classical equivalent. The collective form octopus is usually reserved for animals consumed for food.

http://nl.youtube.com/watch?v=lwAqhThd_EQ

a film here of giant octopus, he's red, so: angry (or at least excited)?

here is said "they run out of energy surprisingly fast ... their blood is not good at carrying oxygen, they need cold oxygen rich waters"

correct?

The idea that octopuses that take on a red color are angry is far to anthropomorphic and over-simplified. If a giant Pacific octopus is "annoyed or irritated" (the closest I will go to calling them actually "angry") they are generally light colored with a bright red stripe through their eye, extending beyond both directions a reasonable distance. There are lots of octopus species and most have unique color displays for different "moods". Most octopuses I have ever worked with have been red colored as a default, calm state.

A lot of octo species flash dark when they're startled or angry, and perhaps some get more reddish as they do it. In general (I think this applies to all the incirrate octos) their has 3 layers of the pigment cells, chromatophores, that are go from light deeper to dark at the surface, over a layer of reflecting cells, leucophores, that are primarily white but are very good at reflecting the color of the environment around them. I don't know where the "red default color" comes from in the GPO (giant pacific octopus) but it doesn't seem to be the "dark" chromatophores all turned on. I suspect that the octos that have a reputation for turning red have reddish "dark" top chromatophores, while other species have more dark brown or black.

I'm not sure where the "octopus blood is a poor oxygen carrier" came from originally, I've run into it quite often, and I think it was a conjecture sometime in the mid-20th century. It may apply to some species in some way, but there are at least some glaring counter-examples: squids have roughly the same blood as octopuses (or octopodes, for the pedantic people) and many of them are very active in low-oxygen environments: in particular, humboldt squids spend a lot of their time in a deep layer of ocean that's very low oxygen, and they, like many squids, have to keep swimming to avoid sinking. If they tired quickly and needed a lot of oxygen, this lifestyle just wouldn't work.

I seem to remember that there are just different regimes of operation for hemoglobin and hemocyanin, and each has strengths and weaknesses. The study that led to this fact getting repeated a lot, if I remember right, studied one aspect in which hemoglobin worked better than hemocyanin, but didn't take into account other factors. Unfortunately, I don't remember the details, but I had heard this claim quite a bit when I first joined TONMO, but the more I've learned, the less it makes sense. I have the impression that most scientists who study cephs don't believe it at this point, but some of the books science journalists and popular science writers refer to make the claim a lot, so it continues to be repeated.

I suspect that the major source for this may be Jacques Coustea's 1973 Octopus and Squid: The Soft Intelligence citing Wells. The passage from Cousteau's book is:

In his excellent work, Brain and Behavior in Cephalopods M.J. Wells devotes a chapter to what he calls "The Downfall of the Cephalopods." He begins by pointing out the perfection of their senses, which, he says, approaches, and sometimes equals, that of vertebrates. Where, then, is the element of downfall? For Mr. Wells, it consists of a "historic" defect of cephalopods which had its origin, among other factors, in a peculiarity of cephalopod blood: it is not red, like that of mammals, but "hyalin," or blue-green. Its volume is considerable, and it is driven through the cephalopod's body by a powerful heart. But the respiratory pigment which fixes oxygen in the blood is not the same as the hemoglobin which gives its color to human blood. There is no iron in its composition, but only copper: hemocyanin. And copper is not as effective as iron in carrying oxygen. Among cephalopods, the total capacity for absorbing oxygen runs from 3.1 per cent to 4.5 per cent, while, among fishes whose respiratory pigment is hemoglobin, it is 10 per cent to 20 per cent.

This explains the phenomenon of "breathlessness" which we so often noted among the giant octopuses of Seattle and the octopuses of Riou when we forced them to swim for any distance.

As much as I admire Cousteau and Wells, I think in the light of modern evidence this is probably an oversimplification. I've noticed that Wells sometimes tends to mix fact, interpretation, and wild speculation on occasion (I have a particular beef with his description of the octopus arm nerves' capacity.)

It is true that octopuses spend a lot of time still and then become active for relatively short periods, and they tend to be ambush predators, so they have bursts of activity. But you could say the same thing about cats.

:octorun: thanks for all the information, everyone, this is really great, am even short of questions for the moment out of sheer speechlessness

to be continued...

This (http://www.liveleak.com/view?i=cee_1189392356) is a short video taken in situ by a well know US ceph scientist, Dr. Roger Hanlon (http://www.mbl.edu/mrc/hanlon/index.html). It is an excellent example of the startled color change seen in octopuses.

So glad they did the slo-mo reverse.

Thanks, I've watched this video many times and it remains incredible. at first i could not believe it was "real" at all, but if a serious professor made it, it must be true!

but if a serious professor made it, it must be true!

:rolleyes:

Octokidwriter, most of us that have kept octos have seen similar reactions in our aquariums but Hanlon filmed this in the water. I can't find the video but there is one about where he discusses taking the picture and its appearance on YouTube (he did not object since it brings positive attention to the ceph world).

Monty, Hanlon is well respected, dedicated and does a lot of in situ work so I am assuming your smerking smiley is based on the general statement and not about Hanlon directly but octokidwriter might not know that.

she doesnt know indeed :rainbow: and gets very confused thinking she makes silly remarks (does she?), but nevertheless dares pose another question:

i have understood octopodes (! learning fast) are very solitary animals, any idea how they communicate with each other?

Monty, Hanlon is well respected, dedicated and does a lot of in situ work so I am assuming your smerking smiley is based on the general statement and not about Hanlon directly but octokidwriter might not know that.

Right, I in no way meant to disparage Dr. Hanlon, just observe that there are cases in which many professors become prone to silliness, so assuming seriousness may not always be appropriate. What professors and what silliness I may be referring to are left to the imagination...

What professors and what silliness I may be referring to are left to the imagination... Fongs up on that comment :thumbsup:

any idea how they communicate with each other
There are several videos and papers about cuttlefish communication through skin patterns and squid communication with color changes - possibly some in the polarized light range. Less is available about octo communication but the old Jacques Cousteau film, Octopus, Octopus suggested that for mating purposes at least, color signals are employed (particularly a darkening around the eyes in males and a striped pattern in females). I did find this article (http://acp.eugraph.com/cephal/) that summarizes most of what I have seen on TV and the net lately and Mucktopus (TONMO member and recent PHD) presented a post-doctorial study (http://berkeley.edu/news/media/releases/2008/03/31_octo.shtml) on the mating sophistication of the Adopus Aculeatus (an Indonesian Octopus) that involves communiction.

that for mating purposes at least, color signals are employed (

aren't octopuses color blind? so how do they distinguish the signals?

Greyscales and contrast, I would suggest? The chromatophores (size variable pigment containing skin cells) themselves are of colours "naturally selected" for optimal matching with their natural surroundings. Plus, at the depth where most octopus interaction occurs, red is grey or even black, as red wavelenghts do not make it down that far (approx. 15 meters in rally clear water).

I've posted two pics of a fish to illustrate the effect, one under ambient light conditions, the other using a flash; watch the pectoral fin especially. The question arises; what good is colour vision down there, anyway?

Ok, that's clear, thanks for the pics, ob.

however, if colors are not necessary as such and really all that matters is the greytones and the patterns, which are so perfect we almost can't imagine they're true (like in that video in this thread), couldn't it also be that there is something quite unimaginable about the "communication" btw them, which we cannot for the life of us see cause we lack imagination to do so?

Always an option. It was not untill fairly recently that we understood insects home in on flowers' nectar through guiding patterns on petals only visible in UV light, that some animals orient themselves on basis of the earth's magnetic field or polarisation patterns in the daylight sky, or that elephants communicate over vast distances using infrasound. It is the flipside of athropomorphism; that we have a blind spot for all the obvious routes of adaptation that lie outside of our own spectrum of abilities; lacking senses sometimes makes us lack sense :wink:

All of the above do rely on actual physical realities, however. Any proposed sensorial perception on the side of the octopus, should logically have it's foundation in that reality. Octopus can taste, sense their surroundings with their arm tips, each arm almost under its own independent control with a large ganglion in place to help coordinate, another one for you to mill over a bit :wink:

octokidwriter,

If you're looking for a hard reference, Hanlon and Messenger discuss sight, skin changes, communication, and other issues in their book "Cephalopod Behaviour."

Both octopuses and cuttlefish (and almost certainly squids) can also see polarization in light, which we can't at all. They're not the only animals can do this, but cuttles are known to use this for communication, since they can control the polarization of their skin, as well. I don't know if anyone has studied whether octopuses use if for communication, but they can learn to make decisions by looking at horizontal vs vertical polarizations, so they can certainly see it. Here's a good writeup: http://www.polarization.com/octopus/octopus.html

As an aside, mantis shrimps (stomatopods) can not only see regular "linearly polarized" light, but also circularly polarized light, and the patterns on their bodies reflect circularly polarized as well. They can't change them on a timescale of seconds the way cuttles can, though. They do have color vision, though, and in fact, where we just see combinations of red, green, and blue, stomatopods can see around 16 different colors, mostly in the blue and ultraviolet range, so at least for them, color vision isn't useless, presumably.

thanks again for the links and the comments

another question on top of all the others: an octopus can creep through a very small hole: "as small as his beak" or "as small as his eye"? I've encountered both versions already.

The eye is flexible, the beak isn't :wink:

It really is the size of their beak, but both are said because you can't really see their beak, but the eyes of a lot of shallow water species are about the same size as their beak. So you can see their eye and its about the size of the smallest hole an octopus could squeeze through.

May I ask some more questions? I give them all at once as they are not too complicated (I hope)

- How long can an octopus live out of the water (on the average?)

- An octopus's beak seems to have a lot of strenght. What does that mean concretely? What can it bite through?

- Would it be correct to say that the octopus arms are lips at the same time?

- the use of "tentacles" or "arms": what is preferable?

Thanks again

May I ask some more questions? I give them all at once as they are not too complicated (I hope)

- How long can an octopus live out of the water (on the average?)
I have had an octopus survive about 15 minutes before I got him back into water. I have seen info at the Seattle Aquarium that GPOs have been known to survive 20 minutes out of water. I would really imagine that it depends alot on the environment. If the octopus is out of water in really hot, dry air, I doubt it would make it 5 minutes. If the octopus could stay moist, (and at the right salinity, so rain is right out), I would image that the next limiting factor would be oxygen. If an octopus could stay sufficiently moist, I would imagine that one could live about 7 hours out of water before it died of "suffocation" (air drowning??), but that is just my semi-educated guess.

- An octopus's beak seems to have a lot of strenght. What does that mean concretely? What can it bite through?
Octopuses can use their break to chip through clam shells, but they generally don't go around crushing things with their beaks. This is one of the amazing things about octopuses. If something is really hard to get into (say a clam that is stubborn about being eaten or something), they use something called a radula in their mouth to drill through the hard parts. The radula is kinda similar to your tongue, but with hundreds of saw teeth on it. These teeth can be moved by muscular action back and forth, creating an action similar to a chain saw, but instead of the teeth traveling all the way around, it is back and forth (I may not have said this as clearly as it could have been put, if you are confused, let me know and I will draw some pictures). With this radula the octopus will drill through these parts, and in the hole inject a small amount of venom that will kill or weaken the animal inside, and make it easy to pull open.[/QUOTE]


- Would it be correct to say that the octopus arms are lips at the same time?
I am not quite sure what you mean by lips. They could be called their tongue, since each sucker has the ability to taste what it touches. (This is one characteristic of octopuses I would hate to have. As a marine biologist I handle some nasty stuff sometimes. I would hate to be tasting it all. It would make gloves more popular. And perhaps they would be flavored... I think I would personally prefer the orange gloves while dissecting....but I digress)

- the use of "tentacles" or "arms": what is preferable?

Thanks again

Arms is preferred for octopus appendages. Technically octopuses have eight arms, and squid and cuttlefish have those eight arms and two tentacles. So the term tentacles in cephalopods is reserved for the appendages that squid and cuttlefish use to capture prey.

I hope that helps a bit...

Think reciprocating saw for the radula...

Thanks. And now for sth completely different, but more of the same: Argonaut: in wikipedia is described as "a sort of octopus", but is it really?

since each sucker has the ability to taste what it touches. ..


does that mean that in fact tasting and touching/feeling are one and the same?

Thanks. And now for sth completely different, but more of the same: Argonaut: in wikipedia is described as "a sort of octopus", but is it really?

I think argonauts do fall under the Order Octopoda (Family Argonautidae) whereas chambered nautilus have their own distinct order (Nautiloidia) which is the same level at which squids and cuttlefish are segregated into their own distinct groups. The common name "paper nautilus" is misleading (not unlike many other common names).

Taste and feeling/touch would be distinct sensations. They come from two different type of receptors. Taste comes from what are called "chemoreceptors". When certain chemicals come in contact with a chemoreceptor, the receptor recognizes the chemical and fires off a nerve impulse. Touch is accomplished with mechanoreceptors. They receptors can tell when the tissue they are place in has been moved or deformed and then shoot off a nerve impulse. So at the level of sense reception the two are distinct.
Now that being said, it is really hard to tell what an octopus actually experiences. There are known cases in human where sensations that are collected independently can be fused in brain into a single sensation, or actually be crossed (seeing sounds, or hearing tastes...). It's called synesthesia. So I really have little clue how the sensory information is processed in the octopus brain. I would image however it is something like your tongue. You can both feel the texture of foods, and taste them at the same time, but they are distinct sensations.

I think argonauts do fall under the Order Octopoda (Family Argonautidae) whereas chambered nautilus have their own distinct order (Nautiloidia) which is the same level at which squids and cuttlefish are segregated into their own distinct groups. The common name "paper nautilus" is misleading (not unlike many other common names).

That's roughly correct, but the "levels" are not quite right. It's detailed at

http://www.tolweb.org/Cephalopoda/19386

but roughly, the living cephalopods, Class Cephalopoda, are divided into Subclass Nautilodea and Subclass Coleoidea. The genus Nautilus are the only living animals in Nautiloidea, although there are very many fossil representatives. All remaining cephs, including the weird argonauts, Spirula, and Vampyroteuthis, are coleoid cephs, which share a lot of traits in common. In addition to the thick external shell (which, arguably argonauta and spirula might have a claim to) Nautilus has 4 gills rather than 2, and a number of other distinctive differences in anatomy that show that it's only distantly related to other living cephs. The separation between argonauts and other octopus species is way down at the Suborder level, where they're really close to all of the octopuses. For comparison, Vampyroteuthis is part of Superorder Octopodiformes which is in Superclass Coleoidea and distinct from Nautiloidea where Nautilus is found, which is a long way of saying that Argonauta is much more closely related to Vampyroteuthis and all squids, cuttles, and octopuses than it is to Nautilus.

Where this gets really interesting is the debates about where the extinct fossil cephs fall in this picture... there's some evidence that the ammonites, despite having external shells like Nautilus, had a lot more traits in common with the modern coleoids, so the division may be less about having external chambered shells, and more about other things like 2 vs 4 gills, ink sacks, hooks/suckers, number of tentacles, types of eyes, and so forth.

Actually, a much better understanding without all the kooky Linnean Latin endings can be seen in this cladogram:

http://www.ucmp.berkeley.edu/images/taxa/inverts/ceph_clad_a.gif

which I lifted (thanks, Roy!) from the UCMP page here: http://www.ucmp.berkeley.edu/taxa/inverts/mollusca/cephalopoda.php

The splits on that "tree" indicate when the groups diverged from one another (keep in mind that the scale of the tree doesn't imply time, just ordering, but we know that the split at the bottom of the tree happened a very, very long time ago from the fossil record.) So [i]Argonauta are over on the far right, in with the octopoda, while Nautilus and its extinct relatives are on the far left. The splits can be thought of as the "last common ancestor," so the last common ancestor between Nautilus and the argonauts was a very long time ago (between 400 and 500 million years ago), while the last common ancestor between the argonaut and other types of octopuses was (geologically) quite recent.

See also http://www.thecephalopodpage.org/evolution.php

I guess that's what happens when I use an old (and out of date?) reference! :oops:

Thanks for setting the record straight Monty! Taxonomy... :bonk:

I guess that's what happens when I use an old (and out of date?) reference! :oops:

Thanks for setting the record straight Monty! Taxonomy... :bonk:

If it makes you feel any better, Steve often has to correct me on using the wrong Latin endings and such, and all that was just poorly-digested regurgitation from tolweb and other references... really, just my attempt to make a small step to making the gibberish slightly less incomprehensible to the general public...

I can't keep all of the terminology and structure straight, I can only remember the general big picture to some extent. I stand in awe of the encyclopedic taxonomic knowledge of Steve, Kat, Roy, and other real experts... :notworth: :grad:

Hello everyone, i've been a while organising all the information i've amassed so...questioning time again!

- In the article "polarised signaling ...and the p-vision of octopuses"(which btw is very difficult for non-scientific me), two kinds of "polarisation" are spoken of: the polarisation of vision (which is still terribly hard for me to understand, despite of all the effort some of you took to make me see the light :), but also "polarised patterns of the skin". Which is not the same as camouflage, as far as i could understand. But then how DO i have to understand this? Something like making oneself invisible?

- Some octopuses have "fluorescent organs"? Are these "organs" or skin? And what exactly do they use it for?

That's it for now. Thanks in advance for the answers!

Hello everyone, i've been a while organising all the information i've amassed so...questioning time again!

- In the article "polarised signaling ...and the p-vision of octopuses"(which btw is very difficult for non-scientific me), two kinds of "polarisation" are spoken of: the polarisation of vision (which is still terribly hard for me to understand, despite of all the effort some of you took to make me see the light :), but also "polarised patterns of the skin". Which is not the same as camouflage, as far as i could understand. But then how DO i have to understand this? Something like making oneself invisible?

- Some octopuses have "fluorescent organs"? Are these "organs" or skin? And what exactly do they use it for?

That's it for now. Thanks in advance for the answers!

1. It sounds like you've mostly got it... polarization is a property of light that, even though it's always there in the light, our eyes don't detect it directly-- we need to use special filters and such to perceive it. For an octopus or cuttle (or a mantis shrimp, or an ant), though, it's as natural to see polarization as it is for us to see color. What they see is a "direction" of polarization. Most often, this is associated with grazing reflections, like the sun off the ocean (which is why fishermen use polarized sunglasses to remove the glare from the water while seeing the fish) but what marine animals usually use them for is seeing outlines of camouflaged animals, like jellyfish, glass squids, and silvery fish that blend into the background. So you can imagine little arrows in the light that define a direction. A lot of light is "randomly polarized," meaning the arrows point all over the place, or it can be "linearly polarized," meaning all of the arrows are lined up with each other. As it turns out, it can also be "circularly polarized" where the arrows follow little helix patterns. Cephalopods don't detect circular as different from random, as far as we know, but they can see the direction of linearly polarized light. Mantis shrimps (stomatopods) can see circular polarization, however.

In the skin case, the skin takes the incoming light, which may be "randomly polarized" and lines up its polarization "arrows" to be "linearly polarized" as its reflected off the skin. Like other skin patterns in cephs, this can be used for displays that are obvious or cryptic... they may want to hide from other animals that can see polarization by trying to hide their silhouettes' polarization, or they may want to make a garish display to catch the attention of a potential mate or intimidate a rival.

2. A lot of cephs do have luminous organs called photophores, but the anatomy varies a lot between species. I think they are usually something like a pocket in or just under the skin, and sometimes (e.g. in Euprymna scolopes) they use symbiotic bacteria to produce the light. Some species have an elaborate reflector and lens system like a projector that directs the light in particular directions, but most have a diffuse glow. Some have eyelid/shutter covers so they can "turn off" their lights, and Vampyroteuthis infernalis has the ability to "ink" a glowing cloud to distract predators as it escapes.

These are used for a number of purposes, although it hasn't been studied enough to know for sure what they all are. Some are used to attract prey or mates... Taningia danae has lights at the ends of each arm that are used to lure and then confuse prey. Many smaller squids use their photophores for "countershading" -- when a predator is below the squid looking up, the light from above makes the outline of the squid clearly visible as a shadow. The countershading photophores light up so that the bottom of the squid is the same brightness as the light coming down from above, rendering it much less visible.

thanks for the extensive answer, monty! the more i learn the more astonished i become...

We will have her keeping one soon. Just to get the correct prospective :mrgreen: of course. And maybe book her hero/heroine will be a good guy, sort of a caped crusader so to speak.

i'm afraid all of you will be in the book some way or other...you may apply for a favorite role in it, so if you have any preferences, do let me know.

in the mean time: a question to keep up the spirits: read somewhere that ink is toxic and even deadly if the octopus should take it in himself. true?

If this were the case, I think we wouldn't be eating too much squid ink coloured pasta :wink: Are you maybe referring to saliva?

"All Ding’ sind Gift und nichts ohn’ Gift; allein die Dosis macht, dass ein Ding kein Gift ist"

Paracelsus

The ink isn't that toxic, but it does burn slightly...more of an irritant than a poison/toxin.

One nice things about octopus, they try to give you a lot of warnings before they actually bite. Having been bitten, I know!

Perhaps this rumor is because sometimes when an octopus is shipped in a small plastic bag, if it inks it can be a health risk? I believe this is more because the unnaturally high concentration of ink tends to coat the gills so it can't get enough oxygen, so it's sort of like being in a smoky room: the smoke would just be annoying in a large room, but if it were in a small closet, it could get hard to breathe.

Still, it's somewhat in the octo's interest to have the ink be some sort of irritant, and to have it interfere with a predators senses (including sight and smell.) Now that I think about it, perhaps some of the brightly colored, and hence toxic looking, cephs have toxic ink rather than a toxic bite... I wonder if anyone's looked at that...

Different glands, but you may be correct.

Different glands, but you may be correct.

Yeah, I just meant that [url="http://en.wikipedia.org/wiki/Aposematism"]aposematism[/a] doesn't have to imply a toxic bite as in blue rings, nor a toxic flesh as in metasepia, but anything where the animal has a defense that causes predators enough grief that either via learning or evolution, the predators avoid the garish animals. We don't know why wunderpus, mimics, and chierchiae have stripes... Roy's mentioned that chierchiae don't live in areas where they could serve as crypsis, so he suspects they could be toxic in some way... but I hadn't considered that that could just as well be ink as venom...

I fail to remember if I suggested this in the past but you might find an idea or two in this (http://www.tonmo.com/forums/showthread.php?t=10712) thread. Of particular humor is this (http://www.tonmo.com/forums/showpost.php?p=99886&postcount=5) one that makes me wish they would do another Airplane spoof based on real life stories.

I want to be the human born with an eye deformity that allows me to see polarized light and befriend the octos (or spy on them).

Steve, of course, needs to be the mad scientist that was infected with cephlobacteria (from not wearing gloves :cephdevil: while messing with dead things) and can change the skin color and texture on his effected digits (sort of a spiderman/hulk concept where he can't control it).

I want to be the human born with an eye deformity that allows me to see polarized light and befriend the octos (or spy on them).

Steve, of course, needs to be the mad scientist that was infected with cephlobacteria (from not wearing gloves :cephdevil: while messing with dead things) and can change the skin color and texture on his effected digits (sort of a spiderman/hulk concept where he can't control it).

I'll see what i can do for both of you. very interesting suggestions, will certainly be taken into account! however, being new and confused about names and identities, may i be so bold as to ask who in this tonmo-maze Steve might be?

I'll see what i can do for both of you. very interesting suggestions, will certainly be taken into account! however, being new and confused about names and identities, may i be so bold as to ask who in this tonmo-maze Steve might be?

Dr. Steve O'Shea of the giant squid fame...

He's even hip enough to have a wikipedia page (http://en.wikipedia.org/wiki/Steve_O'Shea)

Spoil sports! You both had clearer explanations than I was concocting :sagrin:

Spoil sports! You both had clearer explanations than I was concocting :sagrin:

I wouldn't encourage this sort of thing, but technically, anyone can edit wikipedia.

hummm, yes, you have not encouraged this in the past as I recall :wink:

i am impressed! but he's not actually posting on the forum? more some kind of mascotte?

no, seriously, i've read somewhere that the american army is developing a programme using "deviation of light" to make tanks and other unpleasant things invisible (perhaps they could try using in on Sarah P as well), would that have anything to do with "polarisation", in other words did they learn it from the octopuses :bugout:?