Talk:Crab

File:Carpilius convexus is consuming Heterocentrotus trigonarius in Hawaii.jpg to appear as POTD soon

Hello! This is a note to let the editors of this article know that File:Carpilius convexus is consuming Heterocentrotus trigonarius in Hawaii.jpg will be appearing as picture of the day on October 25, 2011. You can view and edit the POTD blurb at Template:POTD/2011-10-25. If this article needs any attention or maintenance, it would be preferable if that could be done before its appearance on the Main Page so Wikipedia doesn't look bad. :) Thanks! howcheng {chat} 17:52, 24 October 2011 (UTC)

Picture of the day

A crab of the species Carpilius convexus (left) feeding on a slate pencil urchin. Crabs are omnivores, feeding primarily on algae, and taking any other food, including molluscs, worms, other crustaceans, fungi, bacteria and detritus, depending on their availability and the crab species. For many crabs, a mixed diet of plant and animal matter results in the fastest growth and greatest fitness.Photo: Mila Zinkova

Consider adding a section on crab anatomy

Since I do not have information on crab anatomy, a simple part-solution is to link to this article: Decapod Anatomy I agree. I am curious about what crabs eat and how they eat. Their claws are their most notable feature but I think the article needs information about their mouth, jaws and teeth (if they have any). Do crabs filter-feed at early stages? Do they generally eat stationary prey?LFlagg (talk) 01:23, 26 December 2014 (UTC)

I can answer at least one of these. They do have teeth! The teeth are not where you think the teeth would be, and is instead in their stomach. Their mouth parts them selves are feathery, relying on the pincers to process the food before consumption. In my experience larval crabs munch on small invertebrates, such as ascidians, however it still needs some study.

The last entomologist to the right (talk) 18:12, 17 December 2022 (UTC)

Deletion of wood eating crab

Surely Wikipedia requires more details and justification before deletion of what appears to be information supported by an in-line reference.__DrChrissy (talk) 18:52, 21 October 2012 (UTC)

No, the burden of proof is on the person wishing to add material. If you can confirm that the animal in question is indeed a (true) crab, then by all means add it. As long as there is reasonable doubt that it refers to a squat lobster instead, I don't think it should be included. --Stemonitis (talk) 05:45, 22 October 2012 (UTC)

But the editor adding the material before your deletion had already taken 'burden of proof' and provided what looked to be a trustworthy reference. Does this mean I can go through WP articles and if I have 'reasonable doubt' I can delete any referenced material? __DrChrissy (talk) 16:24, 22 October 2012 (UTC)

Let's stick to the matter at hand. Does the reference clarify what animal is being referred to? Is it Munidopsis andamanica? Is it a species of Brachyura? --Stemonitis (talk) 16:38, 22 October 2012 (UTC)

I don't know. I do not have access to the original source.__DrChrissy (talk) 16:44, 22 October 2012 (UTC)

No. Nor do I. Since a popular work such as the one cited may well include non-brachyuran animals, it seems quite likely that the wood-eating crab is in fact the widely-publicised M. andamanica. Actually, Amazon preview is now letting me see the book's index, and it does indeed list Munidopsis andamanica for pages 91–92. It is therefore almost certain that the information added does not refer to crabs at all. It pays to be sceptical sometimes. --Stemonitis (talk) 17:03, 22 October 2012 (UTC)

I was not questioning the accuracy of the sentence or your mistrust. I was simply asking whether immediate deletion of a referenced piece of information was appropriate without opening discussion on the Talk page.__DrChrissy (talk) 17:52, 22 October 2012 (UTC)

This talk page is for discussing the content of the article, not a general forum for discussing customs and practices. I think it is clear that in this case it was right to remove the content, since it was about a different taxon. For any other issues, this is not the appropriate place. I can't see that there's actually anything to complain about. --Stemonitis (talk) 18:00, 22 October 2012 (UTC)

Image choice

The following is copied from User:STRONGlk7's talk page, who requested it be continued here.

Please undo your recent edit to the article "crab". Your edit summary of "meaningless editing" is unclear, and cannot be true. Ther previous image was a far better illustration of a crab dish than the replacement you inserted, and that must be the overriding consideration when choosing images to appear in an encyclopaedia. --Stemonitis (talk) 07:20, 21 December 2012 (UTC) Do not write here. Write to the Talk of crab. You said "Better to show a dish only containing crab". So I uploaded crab dishes. Japanese people are eating a crab most in the world. Moreover, those dishes are rich in originality and variety (For example, here). They are important as culture of the crab dish. It is appropriate to show them as an image of the "crab dish". The photograph which you have presented is a very minor dish. STRONGlk7 (talk) 09:33, 21 December 2012 (UTC) In the previous image, the crab dish was large enough to be recognisable. Your image shows some crockery in the distance, and provides very little information about their contents. Better a visible, but (allegedly) minor dish than an invisible one. --Stemonitis (talk) 10:03, 21 December 2012 (UTC) I said you "Do not write here. Write to the Talk of crab.", OK? The full resolution of this image is 4,000 × 3,000 pixels. It is sufficient resolution. And I showed that various kinds of crab dishes existed. The "premise" which you presented is a false charge. Again,"Don't write here". STRONGlk7 (talk) 11:35, 21 December 2012 (UTC)

A collection of dishes, some of which reportedly contain crab

A dish clearly containing crab

The full-size image is less important than the thumbnail that actually appears in the article. At that resolution, the dishes are not recognisable. This makes the previous image a far better candidate. Look at the two thumbnails on the right: which is a clearer illustration of a crab dish for the average reader? I think it is clear that the close-up image of a single dish is far superior to your image of a shop-front, which is poorly composed, poorly illuminated, and fails to illustrate the topic at all well. Even at full resolution, your image is far from perfect, so any potential benefits of a high-resolution image (the alternative is not much smaller) are of secondary importance. --Stemonitis (talk) 12:18, 21 December 2012 (UTC)

Your opinion is meaningless. You have a claim on a whim. I can upload with any photographs. However, You will also set up a new premise, even if I upload a new photograph. You will only allow your favorite photos. Your claim lacks scientific perspective.STRONGlk7 (talk) 00:28, 22 December 2012 (UTC)

mord de rire 80.119.62.196 (talk) 23:31, 21 April 2023 (UTC)

My comments were based on common sense and an understanding of Wikipedia's image use policy. The piture of the crab masala is not my favourite by any means, but it is a better illustration of the topic (this may be what you mean by "scientific perspective"). That is what really matters. It is unfortunate that you cannot see that. --Stemonitis (talk) 08:12, 22 December 2012 (UTC)

these were sooooo tasty...

I don't undersand what science has to do with which image we do either. Stetmonitis' opinion is as valid as anyone else's and it is needlessly confrontational and rude to suggest otherwise. Just to muddy the waters further, here is an image I took. Beeblebrox (talk) 01:04, 23 December 2012 (UTC)

Which is excellent in three photographs? It is needless to say. It is a photograph of a minor dish which you present. Is the crab food of India famous? No. The third photograph only put a crab in a bowl. "Photograph of one kind of dish." Such agreement does not exist anywhere in wikipedia. STRONGlk7 (talk) 03:18, 23 December 2012 (UTC)

• Did you know... That bolding or even enlarging your comments does not make you more correct than anyone else? Did you also know that the comments you are making, bolded or not, are barely intelligible?

Look, this is just a discussion about one image in one article, it is really not that big of a deal no shouting and ranting is not desirable or helpful. The point is that the section is rather brief so there is little room for images, and not everyone agrees that the one you want to put there is the best way to illustrate the concept of crab as food as it shows a wide array of items that, while I am sure they really do contain crab, don't look like much of anything in the picture. Beeblebrox (talk) 19:32, 23 December 2012 (UTC)

why crabs walk sideways

It has occurred to me that crabs walk sideways because they scavenge for food off the seafloor by tasting the ground with their feet. The sideways motion means that they are less likely to miss scraps of food than if they were to walk forwards, if i am right then the footprints of a sideways walking crab should be an evenly spaced pattern of dots with no large gaps or spaces.

The elegance of this answer to this particular question is what attracts me to it, it must be right. Jamesdonkey (talk) 13:04, 31 January 2013 (UTC)

An interesting concept, but where is the evidence for crabs having taste receptors on their feet?__DrChrissy (talk) 18:17, 31 January 2013 (UTC)

I feel obligated to point out at this time that this page is for discussing improvements to the article not for presenting novel theories about crab behavior. There's no way this speculation can be included in the article. Beeblebrox (talk) 03:47, 1 February 2013 (UTC)

Longevity of crabs

Our article Thinking about the immortality of the crab suggests (without citation) that crabs do not age. When I saw that I decided to see what the biologists thought (as opposed to the linguists and authors) by checking this general Crab article. However, there is no mention of the lifespan of the crab in this article... could someone in the know possibly add some info about this? — This, that and the other (talk) 08:00, 2 October 2013 (UTC)

It is fairly well established that lobsters (possibly only tested in Homarus) show negligible senescence, but I have not heard any similar claim for crabs. A cursory search for that kind of thing in crabs also came up blank. It may just be that it hasn't been examined, because many crabs continue to moult during adulthood, as do lobsters, although others show anecdysis, where there is a terminal moult. --Stemonitis (talk) 08:25, 2 October 2013 (UTC)

Interesting. Even if crabs aren't long-lived, has any investigation been done (that you know of) into how long crabs live for in general, in captivity and/or in the wild? — This, that and the other (talk) 12:23, 2 October 2013 (UTC)

Yes, there are various estimates for different species. Longevity in captivity is, perhaps inevitably, longer than in the wild, and varies widely between taxa. The enormous Macrocheira kaempferi may be among the longest-lived, reaching an estimated 50–100 years; some species, including Amarinus laevis and Halicarcinus innominatus are thought to live, generally, for only 1 year. I'm not aware of anything shorter, but apart from economically important species, there is little concrete data. --Stemonitis (talk) 13:34, 2 October 2013 (UTC)

Interesting discussion. Just a quick note. Captivity does not necessarily lead to greater longevity. Elephants (and some other mammals) in zoos die considerably younger than individuals in the wild. I know elephants are not crabs(!), but I thought I would mention it.__DrChrissy (talk) 15:45, 2 October 2013 (UTC)

Physiology/Anatomy?

This article seem to lack information on this. How are their gills constructed? Eyes? How many? That they have eyestalks are only mentioned in the passing... "This is because of the articulation of the legs which makes a sidelong gait more efficient." Well, how are they legs articulated then? How are the internal organs organised?... 83.255.184.212 (talk) 08:32, 8 June 2014 (UTC)

Agree, there is a need for an Anatomy section. It seems there is no standard name for anatomy sections in biology articles, sometimes anatomy is just Anatomy, compare e.g. with the Fish and Crayfish articles. In other articles, anatomy is contained in a Description section, see e.g. the Lobster article. I'll go ahead and add a new Anatomy section and will try to add some information about number of legs, eyes, etc. 2.110.114.86 (talk) 11:54, 2 May 2015 (UTC)

Well... I can't edit this article as it's semi-protected. (strangely there isn't a padlock image in the top of the article indicating that it's protected) So, I'll just leave some thoughts here for changes: The Evolution section should be split up in sections, such as Anatomy, Distribution, Evolution, Name/Etymology. Since crabs are a part of the Decapoda order, they have ten legs, in the form of five pairs of thoracic appendages. The french article is quite good: here is the google translated version of the anatomy related parts (needs much editing): five pairs of legs, the first of which is modified to form a pair of pliers, have a shell rather flat, and a short, wide abdomen under the thorax. The body is segmented, consisting of an exoskeleton more or less hard calcium carbonate , typically the carapace is very large, depressed housing and all organs, this fusion of head and thorax resulting from the process carcinisation (in) , called also brachyurisation (morphological evolution towards a form of crab) . The carapace is formed from the head ( préoral lobe + 4 segments) and pereion (8 segments), the set is wrapped in a continuous shell formed by the pleura last cephalic segment and the tergites of pereion. The pleon (Greek rrXècov, "set sail") of the abdomen (7 segments) is reduced and folded in the face of the carapace inféropostérieure where it fits into a depression that flap in most males is attached by a snap system with two hooks that "pressionnent" two dimples, protecting his first pair of pleopods copulatory . The first 3 pereion segments merged with the head; appendages are the jaw-legged or maxillipeds associated with mouth parts ( mandibles , maxillules, maxilla ). The appendices of the last 5 pereion segments are pereiopods. The first pair of these pereiopods match chelipeds (pliers), generally well developed. The clip includes an orchard mobile, hinging on the propodus consisting of manus and POLEX (colloquially known palm, propodus and orchardgrass form the "hand"). The others are pereiopods locomotive. The appendages of arthropods are in principle biramous formed a endopodite ventral and a more powerful exopodite trickier back often foliated and respiratory role. These two branches are carried by a basilar segment, the protopodite that in crustaceans, is divided into précoxopodite , coxopodite and basipodite (with the exotic and endopodite). In brachyoures the exopodite of pereiopods gill and are housed in the gill cavities in the portions of the carapace. The head has two compound eyes mobiles that can lodge in an orbital slot of the carapace. They are usually after eye stalks (more or less conical tapered rods, articulated at Cephalon, often retractable), giving them a wide field of view (360 ° in ghost crab ). The stomach often divided into two parts called stomach heart and stomach pyloric , is extended by the midgut and accompanied by a large hepatopancreas gland, which summarizes the main digestive enzymes. The cardiac stomach has a masticatory apparatus (gastric mill) consists of highly mobile thickened chitinous parts. Their shell can be filled with dorsal and lateral spines (eg supraorbital spine or épistomienne) spinules, tubers, ridges and hulls which are elements diagnosis . The smallest species described to date is the Nannotheres moorei (taile to 1.5 mm) of the family Pinnotheridae , the largest is the giant spider crab of Japan which can reach up to 3.5 m wingspan, legs extended, 37 cm for the body, and a weight of approximately 20 kg, making it the largest arthropod living. 2.110.114.86 (talk) 12:34, 2 May 2015 (UTC)

Thanks! I made a start with legs and gills in the 'Description' section just now. I think more of the above should be added when someone has the time. Mebden (talk) 20:48, 2 December 2023 (UTC)

Eyes

By coincidence, like the previous poster I was looking for information about eyes and was disappointed not to find anything much. More generally speaking, I also agree with the previous poster that there is insufficient information about anatomy generally. It would be useful if someone knowledgeable about the subject could add this. 109.157.11.138 (talk) — Preceding undated comment added 17:59, 29 July 2015 (UTC)

10 legs?

I suggest that the article mention the number of legs which crabs have.HuPi (talk) 19:15, 18 May 2019 (UTC)

Maybe there should be a part on how lovely the crabs are

arent crabs lovely i like them. — Preceding unsigned comment added by 67.4.192.8 (talk) 03:22, 4 February 2020 (UTC)

What eats crabs

What eats crabs, apart from humans ? Article says what crabs eat, but not what eats them. What predators do they need to avoid ? - Rod57 (talk) 11:56, 10 February 2021 (UTC)

According to a Google search it lists otters and cod as some of the main predators. Unfortunately I can't find any sources that would fit this site's criteria. Or maybe I'm not looking hard enough. 172.112.210.32 (talk) 04:33, 26 January 2022 (UTC)

Octopus. I think I added some text + <ref> about octopus robbing humans' crab traps on [[Octopus]]. Anyhow not just octopus but many things. Invasive Spices (talk) 31 January 2022 (UTC)

"Crab and other Crustaceans" listed at Redirects for discussion

The redirect Crab and other Crustaceans has been listed at redirects for discussion to determine whether its use and function meets the redirect guidelines. Readers of this page are welcome to comment on this redirect at Wikipedia:Redirects for discussion/Log/2023 April 7 § Crab and other Crustaceans until a consensus is reached. Steel1943 (talk) 05:51, 7 April 2023 (UTC)