Talk:Mollusca

Giant squid reference

Shouldn't intelligent invertebrates be qualified since none have been observed alive (except their juveniles recently). Instead, perhaps it could be stated "octopus and squids are among the most intelligent invertebrates. The giant squid is the largest invertebrate, but only the tentacles and carcasses of the adults have ever been observed.. Something along those lines. --rgamble

I agree completely. Do you want to make the change? AxelBoldt~

I've done so. Minor nit, and the extrapolation was probably valid but... you never know. ;) --rgamble

I don't think it would do any harm to include a list of the different mollusks with links to their articles. Anyone? palefire

No I don't think that would be a bad idea. Avatar of Nothing 21:29, 17 March 2007 (UTC)Avatar of Nothing

Titling

Pretty much every occurrence of the term in the article itself is "mollusc" not "mollusk"; would it be more appropriate to move the page to Mollusc? Shimgray | talk | 20:20, 17 December 2005 (UTC)

Check the history, it seems to be one of those US vs The Rest spelling fights. --Paul 14:42, 26 December 2005 (UTC)

Ah, yes. What links here shows about even for mollusk/mollusc, so no help there, but the technical term is "mollusca"... huh. Either way, it'd be nice for the article to agree with the title. Shimgray | talk | 15:28, 26 December 2005 (UTC)

How about Mollusque ... which hasn't been used for centuries? I agree that the title should agree with the spelling used in the article. My preference is for mollusc but it's not up to me. According to WP:MOS, we should settle on whatever was the first spelling. Jimp 10Feb06

Looking back, it was originally a redirect to Mollusca, then that page was moved here "to the English title". Shimgray | talk | 16:04, 10 February 2006 (UTC)

Then looking back at the history of Mollusca shows something quite interesting. The very first comment comes from User:TrickyP who writes "Changed mollusc to the preferred spelling, mollusk." I can't see any eariler version but presumably it had mollusc. I don't know whether Tricky was aware that mollusk is not the preferred spelling outside the US. Jimp 06:29, 15 February 2006 (UTC)

I vote for Mollusc. There are more non-Americans than Americans. And science is international.

I vote for Mollusk. "sk" is usual, i.e. "desk", "task", "whisk", "risk", "mask" etc., "sc" is not i.e. "disc" (the only example I can think of). 64.194.44.178 19:16, 1 April 2006 (UTC)

The difference between "--sk" words and "--sc" words is etymology. The ones with "--sc" usually come from the Greek or Latin, the ones with "--sk" are usually Germanic, or else French, as a replacement for "--sque". So "disc" from "diskos", a Greek word for the round throwing object, spelled in Latin as "discus". Compare "whisk" with "viska", the same word in Swedish, or "mask" with "masque", almost the same word in Old French. "Mollusc" was coined by Linnaeus from the Latin but the original Latin word "molluscus" related to "mollis", meaning soft (as in the eider dusk, Somateria mollissima, who's species name means "most soft", a reference to its feathers). For whatever reason American English has replaced the "--sc" endings with "--sk" while British English keeps them. Since the word has no great antiquity, there isn't really a traditional one and both are used in science (though American journals tend to favour American spellings, and British journals British spellings). I happen to prefer mollusc because it is closer to Mollusca, but really I couldn't care less. Cheers, Neale Neale Monks 21:08, 9 November 2006 (UTC)

FWIW, I'm American and I was faintly startled to discover that "Mollusk" is supposedly our favored spelling. I've never seen any authority, U.S. or otherwise, spell it with the K. Does somebody have some citations for scientific publications using this spelling?Nentuaby (talk) 00:53, 11 April 2008 (UTC)

The following discussion is an archived debate of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the debate was move. —Nightstallion (?) ^{Seen this already?} 14:33, 22 April 2006 (UTC)

Requested move

Mollusk → Mollusca |→ Spaully°τ 00:18, 17 April 2006 (GMT)

Rationale: Per WP:MOS which prefers the use of nationally neutral terms ("Where varieties of English differ over a certain word or phrase, try to find an alternative that is common to both." - see also Airplane and Aeroplane), I am posting a request at WP:RM to move this page to Mollusca, the name of the phylum this page deals with. I tried to move it myself, but the previous edit history at Mollusca dissallows this. All of your input would be very welcome. |→ Spaully°τ 00:12, 17 April 2006 (GMT)

Survey

Add *Support or *Oppose followed by an optional one-sentence explanation, then sign your opinion with ~~~~

• Support. |→ Spaully°τ 00:23, 17 April 2006 (GMT)
• Oppose. Should we move Cat to Felis, Dog to Canis, Lion to Leo, etc?? Georgia guy 00:30, 17 April 2006 (UTC)
• Support. WP:TOL advocates use of common names where they exist (although I'd have preferred the spelling mollusc, but it's too late for that now. --Stemonitis 13:21, 20 April 2006 (UTC) Hang on, I've just re-read the arguments. A nationally neutral term like "Mollusca" seems justified in this case. --Stemonitis 13:23, 20 April 2006 (UTC)
• Support. While it Wikipedia's policy certainly does prefer the usage of common name, this seems like a reasonable time to make an exception, as a compromise between two national spellings, however, we will still be left with the decision of which term to use in the body of the text, because, while mollusca makes a decent article title, it doesn't work well as a noun in a sentence.Cerealkiller13 16:21, 20 April 2006 (UTC)
• Support. Bactram 15:38, 21 April 2006 (UTC)

Discussion

Add any additional comments

Georgia guy - this move is because American english uses 'mollusk ' whereas the rest of the world uses 'mollusc '. There is no such difference with dog and cat. Given this, please read this part of the MOS for an explanation. |→ Spaully°τ 10:04, 17 April 2006 (GMT)

In response to Cerealkiller13's query about which spelling to use - there seems to be no reason to change the spelling from the current one (whatever that might be), provided it's consistent. --Stemonitis 07:24, 21 April 2006 (UTC)

The above discussion is preserved as an archive of the debate. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Squid

Recent studies have found that the collosal squid is now the biggest inverterbrate and I thought i'd just let you know.

How Many Species?

How many species of Mollusc are there? Phylum says 70,000. The introductory para says 112000, with a reference. Later on, the article says 250000. Can someone who knows the correct number please fix this? Thanks!

Short review about how many mollusca species exist is at http://www.mollusca.cz/malakologie/pocet.htm Unfortunatelly it is in Czech language. It is my article, I can translate it if you want. I have counted 82 067 species. --Snek01 18:40, 22 October 2006 (UTC)

Recent symposium volume says about 200,000 species. Reference is:

• Ponder, Winston F. and Lindberg, David R. (Eds.) (2008) Phylogeny and Evolution of the Mollusca. Berkeley: University of California Press. 481 pp. ISBN 978-0520250925.

My suggestion is to go with this total. I have placed this in the taxobox, but other numbers are sprinkled throughout the article. --Wloveral (talk) 02:54, 24 May 2008 (UTC)

There still remains wildly differing numbers of extant mollusc species in the article: ca100,000, ca200,000, >250,000, and 160,067. Can someone please rationalise this. In particular, the Classification section contradicts itself. GrahamBould (talk) 19:34, 4 July 2008 (UTC)

Hi GrahamBould. I've put the same question down below together with estimates from two different student textbooks. I'm happy to change the article to one or the other but would quite like input from someone with expertise!  :-) --Plumbago (talk) 06:04, 5 July 2008 (UTC)

Science = Mollusca/Mollusk

A mollusk come from a Latin word MOLLUS that means " soft".

A coelom is a fluid filled cavity that develops within the mesoderm.

A mollusk has a soft body from a Latin word mollus meaning soft which is generally protected by a very hard calcium containing shell.

Bellerophontidae

Im not sure where to put this, some authors class this as a seperate class and not a gastropod like the new classification! Where can it go? Enlil Ninlil 04:38, 12 January 2007 (UTC)

Pearl-Guide.com site

Firstly, it's a commercial site, so should be handled carefully. Secondly, it contains several mistakes:

1. The tree structure implies Aplacophora and Polyplacophora are not Molluscs
2. Monoplacophora and Scaphopoda are shown outside of Conchifera, when they're usually part of it
3. Below the Conchifera branch of the tree, incorrect relationships between the groups are implied

Some of these points are probably a feature of the tree design (and the need to have it fit on a webpage) rather than any misunderstanding on the part of its creator. However, as the page offers very little useful information and is misleading, I'm removing it again. Sorry, --Plumbago 18:05, 25 January 2007 (UTC)

Slime / excretions

I think someone (preferebly an expert) should put something up about what is in the slime that snails produce and what is its function. Superruss.

misleading

I think that most people that are typing in Mollusca they will be looking for the Bivalve Mollusk, I think there should be a redirect for the people that are looking for the commonly named [Bivalve] Mollusk. Russianfriend742 15:29, 2 May 2007 (UTC)

Big Squids

The giant squid, which until recently had not been observed alive in its adult form,[3] is one of the largest invertebrates; however the colossal squid is even larger.

Wouldn't it be easier just to say that the colossal squid was the biggest? —The preceding unsigned comment was added by 68.32.235.75 (talk) 23:51, 2 May 2007 (UTC).

Mollusc shells

The animal shell article, although better than it was, is still in dire need of an expert's help. Would anybody care to have a go at cleaning up the "Mollusc" section there? My inclination is to use Wikipedia:Summary style, leaving a paragraph or two at Animal shell with a brief overview of things that are common to all mollusc shells, then move more of the chemical and anatomical details to a separate article -- perhaps at sea shell (currently a redirect). That article, in itself, could be a summary of Gastropod shell, Bivalve shell, etc.

Anyway, I've done what I can; thank you if you can provide further help! — Catherine\^talk 16:55, 23 June 2007 (UTC)

Pain and Nerves

Do molluscs have nerves? Do they feel pain? —The preceding unsigned comment was added by AThousandYoung (talk • contribs) 21:25, August 22, 2007 (UTC).

The answer to the question of whether molluscs feel "pain" will depend on how you choose to define the term, but they certainly have a sense of touch, and when they encounter harmful touching they will react accordingly.

How do molluscs breathe on land?

It would be useful if this article could contain a description of how land-based molluscs, or beached acquatic molluscs, breathe: see, for example [1], [2] -- The Anome 09:20, 29 October 2007 (UTC)

Molluscan classes

How's about this for an alternative to the current list of molluscan classes?

Class	Major organisms	Extant species	Distribution
Caudofoveata	worm-like organisms	70	deep ocean
Aplacophora	solenogasters, worm-like organisms	250	deep ocean
Polyplacophora	chitons	600	rocky marine shorelines
Monoplacophora	limpet-like organisms	11	deep ocean
Gastropoda	abalone, limpets, conch, nudibranchs, sea hares, sea butterfly, snails, slugs	40,000 - 150,000	marine, freshwater, land
Cephalopoda	squid, octopus, cuttlefish, nautilus	786	marine
Bivalvia	clams, oysters, scallops, mussels	8000	marine
Scaphopoda	tusk shells	350	marine
Rostroconchia †	fossils; probable ancestors of bivalves	extinct	—
Helcionelloida †	fossils; snail-like organisms such as Latouchella	extinct	—

This information is little messy in the article at present, so I figure a table might add some structure. I've removed some information about the example gastropods, but I reckon that should really be picked up by the gastropod article itself. Also, I've juggled the order of the classes to follow the ancestral order illustrated (though I've stuck the extinct species out on their own at the end). Anyway, if people like this (or no-one replies), I'll import this into the article. Please feel free to make edits to it. Cheers, --Plumbago (talk) 08:00, 13 May 2008 (UTC)

Excellent. I wonder whether the Distribution could be expanded to indicate whether free swimming or sedentary (may be too difficult given that scallops can swim too!!). Cheers GrahamBould (talk) 22:38, 15 May 2008 (UTC)

Hi there. Thanks for taking a look at the table! I suppose it could be expanded in the way you suggest, but I'd concur about the difficulty vis-a-vis even sedentary organisms swimming. Anyway, I'll add the table above to the article. --Plumbago (talk) 11:44, 20 May 2008 (UTC)

Further to the above, and since I'm wildly out of date, I've had a poke around a couple of modern-ish textbooks and now have a couple of alternative schemes for classification at the class level:

Class	Extant species		Class	Extant species
Chaetodermomorpha	70		Aplacophora	~370
Neomeniomorpha	180
Monoplacophora	?		Monoplacophora	~25
Polyplacophora	550		Polyplacophora	~1000
Gastropoda	~77000		Gastropoda	~70000
Bivalvia	~20000		Bivalvia	~20000
Scaphopoda	~350		Scaphopoda	~900
Cephalopoda	~650		Cephalopoda	~900
Total	~98800		Total	~93195

The scheme on the left stems from:

Barnes, R.S.K., Calow, P., Olive, P.J.W., Golding, D.W. and Spicer, J.I. (2001). The Invertebrates, A Synthesis (3rd Edition), Blackwell Science, UK.

The scheme on the right stems from:

Brusca, R.C. & Brusca, G.J. (2003). Invertebrates (2nd Edition), Sinauer Associates Inc., MA, USA.

Neither seems to include the wholly extinct classes, the Rostroconchia and the Helcionelloida, although Brusca & Brusca (2003) do refer to around 70000 extinct mollusc species. Anyway, I'll try to synthesise this information into the main article, but wanted to log it here (a) so I didn't lose it, and (b) to attempt to elicit more informed views of molluscan taxonomy! Cheers, --Plumbago (talk) 14:49, 20 May 2008 (UTC)

Reproduction?

There's no mention of any kind of reproduction in this article, which I think is an important part of any subject related to biology. Maybe you could do something like the article for sponges, where there is a section for "Ecology and Reproduction". Hippie Metalhead (talk) 01:58, 16 May 2008 (UTC)

Sources, etc.

Definition

• Evidence for a clade composed of molluscs with serially repeated structures: Monoplacophorans are related to chitons (2006) : "Molluscs (snails, slugs, clams, mussels, squids, octopuses, chitons, etc.) exhibit the largest disparity of all animal phyla and rank second behind arthropods in species diversity." "In fact, the disparity of mollusc body plans is so great that it is quite difficult to find a single trait shared by all seven classes of molluscs (13)."
• From Brusca & Brusca. Invertebrates (2nd ed.)., p 702:
  • Bilateral symmetry - hmmm
  • Coelom limited to small spaces around nephridia heart & part of intestine - I'll have to check how that differs from e.g. arthropods.
  • Principal body cavity haemocoel - applies also to arthropods.
  • Dorsal concentration of viscera (visceral mass) - might be the main one, IIRC one source I found was confident only about this one.
    apparently not in aplacophora (Ruppert et'al, Inv. Zoo. p291)
  • Y Body covered by mantle; mantle cavity contains ctenidia, nephridiopores, gonopores & anus - I'll check out aplacophora, they're "the usual suspects".
    mantle; mantle cavity contains ctenidia, nephridiopores, gonopores & anus (Ruppert et'al, Inv. Zoo. p291)
  • Y Mantle shell glands secrete calcareous spicules, plates or shells - ditto
    aplacophora secrete spicules (Ruppert et'al, Inv. Zoo. p291)
  • Heart in pericardial chamber, separate ventricle & atria - might be promising.
  • Large, well defined muscular foot, often w/ creeping sole - would include our Cambrian conundra.
  • Buccal region w/ radula - not in bivalves or aplacophora.
    aplacophora have buccal cavity, but 20% lack radula (Ruppert et'al, Inv. Zoo. p291). Bivalves have no buccal cavity!
  • Complete gut with regional specialisation, incl. large digestive ceca - promising, must check aplacophora.
    no caeca in some aplacophora (Ruppert et'al, Inv. Zoo. p291)
  • Large complex metanephridia - must check what this means!
    aplacophora no nephridia (Ruppert et'al, Inv. Zoo. p291)
  • Protostomeus embryos - hmmm
  • Trochophore larva, usually veliger - hmmm.
• From Ruppert et'al, Inv. Zoo. (general: p 284-291. aplacophora: p291-292; bivalves: p 396ff)
  • Y 2 pairs of main nerve cords, except 3 in bivalves.

-- 82.34.73.184 (talk) 21:11, 29 September 2008 (UTC)