Talk:Cephalopod

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is jet propulsion the primary method of locomotion for octopi?[edit]

from the article: "Cephalopods' primary method of movement is by jet propulsion", is this true of octopi? i think this statement may not be true and may need to be qualified. as i understand it, octopi can use jet propulsion, but are primarily walkers. - UriBudnik

For cephalopods as a group, jet propulsion is the primary form of propulsion. However, you are correct to note that many octopusses (although not all of them) will use some form of walking as their typical short-distance locomotion. For longer distances, they will still use jet propulsion. - UtherSRG (talk) 13:18, August 22, 2005 (UTC)

Even so you might want to clarify the underwater aspect; I can imagine some brilliant people out there hearing about cephalopods in flight for 50 meters and think OMG FLYING OCTOPODS - Guest User, 11:20, Dec.16/09 —Preceding unsigned comment added by 99.231.178.112 (talk) 16:20, 16 December 2009 (UTC)

Colorblind[edit]

File:Colorblind5.png
Someone who is tritanopic might not see this number.

"They are probably colorblind"? How can this possibly be? If they were colorblind how could they possibly copy they color of their surroundings? —Preceding unsigned comment added by 69.137.223.3 (talkcontribs) 8:27PM December 19, 2005

It's true. They are colorblind. - UtherSRG (talk) 11:50, 20 December 2005 (UTC)
How do you test this? Show them cards with numbers and tell them to raise their tentacles?
Maybe they are just bad in math, (or prefer the octal notation :-) Petri Krohn 21:59, 6 April 2006 (UTC)

I put {{fact}} by that claim for that very reason brought up by 69.137.223.3. That claim must be cited individually. -Will Pittenger 07:34, 17 November 2006 (UTC)

The citation covers the entire paragraph. I added a separate instance of it after the specific claim, though the result is ugly. —Celithemis 07:40, 17 November 2006 (UTC)

In that case, perhaps we should expand that part into a complete subsection. That way we could explain how they can get their skin to match the colors of what is around them without them seeing the colors in question. That needs some sort of explanation still. -Will Pittenger 08:05, 17 November 2006 (UTC)

Better. I guess the main problem was that it was assumed that we could read the source. For that, though, you would need to subscribe to the correct publications and understand what they say. That is not me. Will (Talk - contribs) 08:23, 17 November 2006 (UTC)

Can we be given a reference which proves cephalopods to be colourblind? Because as far as I am aware, they use colour for communication Seascapeza (talk) 08:03, 10 March 2009 (UTC)

Further rummaging through references (and especially Mark Norman's handy Cephalopods, a world guide ISBN 3-925919-32-5) has revealed that, as at 2000, when the book was published, the conclusion was that although cephalopods can see tone, they cannot see colour. This will explain the bright coloured/pale coloured mating displays. However, a more recent text (Brusca and Brusca (2002) Invertebrates ISBN 0-87893-097-3) states that there is some experimental evidence which suggests they can see in colour. I am unable to check on which reference they give is the experimental evidence in question. Ruppert, Fox and Barnes, in Invertebrate Zoology 7th ed. (2004) say more definitely that although there are a few exceptions cephalopods have only one visual pigment, and that in general they cannot see in colour. So it sounds like it's tones only rather than actual colour, although shallow water cephalopods apparently (Ruppert & Co again) have a protective yellow pigment in their retinas which reduces UV damage. Seascapeza (talk) 09:15, 10 March 2009 (UTC)

Martin Wells, a respected zoologist who did early pioneering work in cephalopod intelligence, found that octopuses (Octopus vulgaris, I think) could not distinguish objects on the basis of colour. That is, if the octopus was presented with two objects of the same size, shape, texture and tone but of different colours, and was rewarded by being given a crab for choosing one colour and punished by electrocution for choosing the other, that they could not learn to make a consistent choice (ie the results were consistent with random selection). The results can be found in the book, "Brain and behaviour in Cephalopods." (see here). Research has only been done on a very small number of species due to the difficulty of catching them (particularly rare or deepwater species) without exposing them to a lethal level of trauma and keeping them in aquariums. K-22-22 (talk) 20:58, 10 March 2009 (UTC)

There are many references available for cephalopod colour-blindness (except for the firefly squid), experimentally approached from a few different angles. Here is to list a few I have come across:

  • Paul K. Brown & Patricia S. Brown (1958) "Visual Pigments of the Octopus and Cuttlefish" In: Nature, vol:182 iss:4645 pg:1288-1290
The authors measure spectral absorbtion using retinal extracts from Octopus vulgaris and Sepia officinalis and suggest that there is only one photoreceptic pigment (rhodopsin) with a maximum absorbances at 475nm (Octopus vulgaris) and 492nm (Sepia officinalis).
  • James Bellingham, Alex G. Morris & David M. Hunt (1998) "The rhodopsin gene of the cuttlefish Sepia officinalis: Sequence and spectral tuning" In: Journal of experimental biology, vol:201 iss:15 pg:2299-2306
The authors study the rhodopsin gene of the cuttlefish, which shows that only a single type of rhodopsin is expressed. Since the spectral sensitivity of visual pigments can be predicted from the amino acid composition of the opsin they were able to model the maximum absorption and they proposed a max absorption spectra of 492nm, which agrees with Brown and Brown(1958).
  • N.J. Marshall & J.B. Messenger (1996) "Colour-blind camouflage" In: Nature, vol:382 iss:6590 pg:408-409
The authors took advantage of the fact that cuttlefish try to camouflage on any background they are placed. They presented cuttlefish with gravel substrates of varying colors: red, white, blue, and yellow. These authors suggest that while red and white gravel would appear as a strong contrast to the cuttlefish visual system, yellow and blue would not appear as different contrasting shades of color. They reported that cuttlefish produced a bold coarse mottled pattern when placed on red and white gravel, presumably in an attempt to "match" the coarse patterning of the gravel, whereas the animals showed an overall uniform pattern on blue and yellow gravel, suggesting that these shades did not appear as two contrasting colors but instead as a uniformly colored gravel background.
  • Lydia M. Mäthger, Alexandra Barbosa, Simon Miner, Roger T. Hanlon (2005) "Color blindness and contrast perception in cuttlefish (Sepia officinalis) determined by a visual sensorimotor assay" In: Vision Research, vol:46 iss:11 pg:1746-1753
The authors carried out two experiments. In the first they created 16 checkerboard substrates in which 16 grey shades (from white to black) were paired with one green shade (matched to the maximum absorption wavelength of S. officinalis sole visual pigment, 492 nm), assuming that one of the grey shades would give a similar achromatic signal to the tested green. In the second experiment, they created a checkerboard using one blue and one yellow shade whose intensities were matched to the cuttlefish's visual system. In both experiments they tested whether cuttlefish would show disruptive coloration on these checkerboards, indicating their ability to distinguish checkers based solely on wavelength (i.e., color). They show clearly that cuttlefish must be color blind, as they showed non-disruptive coloration on the checkerboards whose color intensities were matched to the Sepia visual system, suggesting that the substrates appeared to their eyes as uniform backgrounds.

For general reading on cephalopods these books are good and include lots of useful references, enjoy:

  • N. Joan Abbott, Roddy Williamson, Linda Maddock (1995) "Cephalopod Neurobiology" Oxford University Press ISBN: 0198547900
  • Marion Nixon & John Z. Young (2003) "The brains and lives of Cephalopods" Oxford University Press ISBN: 0198527616
  • Roger T. Hanlon & John B. Messenger (1996) "Cephalopod Behaviour" Cambridge University Press ISBN: 0521420830
  • Martin Stevens & Sami Merilaita (2011) "Animal camouflage: mechanisms and function" Cambridge University Press ISBN: 0521199115

--Mnakamura (talk) 02:38, 6 November 2011 (UTC)

Redundant[edit]

" Teuthology, a branch of malacology, is the study of cephalopods and teuthologists are the scientists who study them." read the article. I've removed "and teuthologists are the scientists who study them." It was redundant. It's just a matter of -ology and -ologist these are very common suffixes. 12:15, 9 February 2006 (UTC)

Tautology then ! --195.137.93.171 (talk) 19:00, 7 January 2011 (UTC)

Including fossil cephalopods[edit]

The main article for cephalopods seems to almost totally ignore extinct forms, which is a pity since the class has such a fine fossil record. Indeed, the known fossil species far outnumber the living. There are already some nice Wikipedia articles about ammonoids, nautiloids, & belemnoids. Can we integrate them better into the main cephalopod article? Cephal-odd 05:23, 7 March 2006 (UTC)

"IQ"[edit]

I didn't check the references, but this statement seems kind of dubious:

"They are regarded as the most intelligent of the invertebrates with an average IQ of 30 equvalent in humans." --134.134.136.5 00:41, 2 August 2006 (UTC)

Greek[edit]

The article read:

(Greek Κεφαλόποδον (kefalópodon), plural Κεφαλόποδα (kefalópoda); "head-foot")

OK, I'm pretty sure that Κεφαλόποδον is a modern Greek form (and this is supported by the transliteration in f instead of ph usual for Ancient Greek). Unfortunately, in Ancient Greek, so far as I can tell, the singular of the word should be κεφαλόπουν (like the attested τὸ τετράπουν "the quadruped"), which is just absurd, so I just removed all reference to the singular. I hope no one minds. --Iustinus 02:31, 7 September 2006 (UTC)

Encephalopod[edit]

Currently redirects to Xenomorph (Alien) but [1] claims it is archaic for cephalopod. Vagary 19:44, 21 September 2006 (UTC)

early cephalopods & Tommotia[edit]

The Early Cambrian fossil Tommotia was recently added to this article as a basal cephalopod. The shell does look vaguely like that of some early nautiloids, but as far as I know the oldest generally accepted cephalopod is Plectronoceras from the Late Cambrian. Does anyone have a reference that supports the assignment of Tommotia to the cephalopods? Cephal-odd 00:31, 24 September 2006 (UTC)

Color of Cephalopod blood?[edit]

I heard that cephalopods are supposed to have clear blood with a copper based compound instead of hemoglobin. Is that true? -Will Pittenger 01:51, 17 November 2006 (UTC)

I should also ask if this is something that belongs in the article. Can it be cited? Will (Talk - contribs) 07:40, 17 November 2006 (UTC)

I believe that the active lifestyle of Cephalopods requires not only a closed circulatory system but a hemoglobin based blood cell instead of the amoeboid ones in other simple animals. 75.37.64.126 00:00, 29 April 2007 (UTC)

Cephalopod blood is indeed blue, because of the copper-based respiratory pigment they have in their blood. See Norman, Mark (2000) Cephalopods, a world guide p.6 ISBN 3-925919-32-5 Seascapeza (talk) 08:35, 10 March 2009 (UTC)

Please cite each fact[edit]

I noticed that most people working on this page rely on the References section. It is written so that there is no way to tell what is being cited. Please put cite links in, preferably with the <ref> tag. Will (Talk - contribs) 07:39, 17 November 2006 (UTC)

Nonsense. True, verification of stated facts is desired (necessary if you prefer), but a series of obviously related facts need only be referenced once. In an article with multiple sections it should be obvious as to which section a particular reference refers to. J.H.McDonnell (talk) 15:34, 8 September 2010 (UTC)

semi edit of reproduction[edit]

I have added in a section on reproductive behaviour/life cycle. I have not integrated my additions with the first paragraph of the section, primarily because I couldn't work out how to make the two sections flow nicely. Help, anyone? Seascapeza (talk) 08:11, 10 March 2009 (UTC)

Classic error[edit]

The article committed a famous schoolboy howler in supposing the plural of Octopus might be Octopi. It would be, if the word was latin in origin. However, its origin is classical Greek, as is Cephalopod. The 'feet' ending coumes from 'pous' (I'll use our letters for simplicity). The plural of pous is podes, usually written 'pods' in English. So cephalopods is fine, whereas octopi is simply wrong. Don't feel bad about it; remember that in Goldfinger Ian Fleming has Pussy Galore saying "My father was an expert on octopi", thus proving that he wasn't, or he would have taught her the right word!

The plural of Octopus is Octopods, or Octopodes if you must. Dictionaries also offer the rather inelegant Octopuses. Macdonald-ross (talk) 08:59, 28 March 2009 (UTC)

This is a particularly appropriate comment. After changing edits by 99.225.28.182 from 'octopi' to 'octopodes', my edits were subsequently changed again back to 'octopuses' almost immediately by Mgiganteus1. This is quite OK by me, since this is the most commonly accepted correct pluralisation of the word 'octopus'. Acceptable form for general word use on any Wikipedia page should at least be a correct one, unless part of an explanation as to why it is unsuitable. There is an excellent discussion of this issue on page Octopus. Peter b (talk) —Preceding undated comment added 07:08, 12 December 2009 (UTC).
Out of curiosity does anyone have reliable citations that state Octopi is not a viable plural term? I have looked through the archives here and at Octopus and I havent actually found anything other then what appears to be OR research as to what the plural forms can and cant be, never with any backing citations. --Kevmin § 06:25, 22 September 2010 (UTC)
Kevmin, have you checked the Terminology section of our Octopus article? mgiganteus1 (talk) 07:18, 22 September 2010 (UTC)

Can they fly[edit]

It says some cephalopods can fly up to 50m. It even has a citation, (which doesn't actually support the statement. ) Is this true? Polarpanda (talk) 12:22, 7 December 2009 (UTC)

It may very well be true, but I think there needs to be a better description of how they are able to accomplish the feat. Certainly not from a standing stop. They must jet through the water and then break the surface. The statement needs to be qualified. Neptunerover (talk) 22:39, 7 December 2009 (UTC)

The statement "50m" is a reference to a reference within the reference. The original data comes from this book: Lane, F.W. (1957) "Kingdom of the Octopus: the life history of the Cephalopoda" London : Jarrolds. The statement 50m is not actually the author's observation but in 1947 of the species of squid Onychoteuthis banksi (1–3 in number) which flew for 45–55m, various observations by Thor Heyerdahl in his Kon-Tiki voyage in the Pacific. More recent recordings in the cited paper in the article observe 7-15m by various species. I think its probably better to say in the article that squid have been observed to glide tens of metres, and then list a few citations after that for any people curious rather than hyping it up by giving the maximum recording which is slightly dubious.--Mnakamura (talk) 03:21, 6 November 2011 (UTC)

Reference to broken DOI[edit]

A reference was recently added to this article using the Cite DOI template. The citation bot tried to expand the citation, but could not access the specified DOI. Please check that the DOI doi:10.1111/j.1096-.x has been correctly entered. If the DOI is correct, it is possible that it has not yet been entered into the CrossRef database. Please complete the reference by hand here. The script that left this message was unable to track down the user who added the citation; it may be prudent to alert them to this message. Thanks, Citation bot 2 (talk) 04:26, 30 April 2010 (UTC)

I find that using a URL link or simply querying the reference, not to mention using a good old fashion library source, works a lot better for me than trying to use the DOI method. J.H.McDonnell (talk) 15:42, 8 September 2010 (UTC)

Overhaul needed[edit]

This article is full of facts but is poorly organized and burdened with excessive references, meaningless notations, and superfluous links. Related topics should be combined and where necessary separated from unrelated. Facts should be reviewed. It short, it needs a good overhaul. J.H.McDonnell (talk) 15:28, 8 September 2010 (UTC)

referring to picture with caption: "Octopuses swim headfirst, with arms trailing behind"[edit]

Cephalopod arms/feet are in the same place as their head (hence, "head-feet"). How can they then swim headfirst, with arms trailing behind? —Preceding unsigned comment added by 69.2.171.36 (talk) 23:41, 14 November 2010 (UTC)

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bioluminescence[edit]

This article contradicts itself in the 'Use of light' section where it first says "bioluminescence is produced by bacterial symbionts" and later says "It is not certain whether bioluminescence is actually of epithelial origin or if it is a bacterial production". Tweisbach (talk) 05:17, 24 December 2015 (UTC)