Purple Octopus - using citizen science to discover marine interactions
This is the entity page showing aggregated messages and images for the named entity.

Carcinus maenas

(Linnaeus, 1758)

Annette Graves With some marine creatures their beauty is best caught out of the water, such as the Green Shore Crab, Carcinus maenas

Message posted on Scubashooters.net on 06 Mar 2013
Cathal McNaughton Carcinus maenas at 900 feet above sea level within otter spraint. Approx 2 miles from the sea. A large stream connects a small network of upland lakes with the nearby coast and otters are to be seen at the lakes and the in the vicinity of the outflow of the river. This spraint was found at a regularly used latrine beside one of the hill loughs on Saturday 17th Nov. Garron Plateau, NE Co. Antrim.

Bernd Lipsius

Liz Morris A very berried Carcinus maenas, green shore crab. Imagine if all those babies actually made it - loads of crabs! And pretty cool larvae too :)

Liz Morris note seagrass in the background!

Message posted on Seasearch North Wales on 16 Apr 2012
Elly Jeurissen Common green crab @ saltwater Lake Grevelingen, The Netherlands Canon G12 in Canon WP-DC34 UW-housing; F8; 1/500; ISO 80 Inon UCL-165 macro lens, Single strobe, Sea & Sea YS-01

Stuart Pearce My old friend Carcinus maenas, done some research into their immune system, great shot :)

Elly Jeurissen Really? Interesting! Do you have some more information on that topic Stuart?

Stuart Pearce Have some shots (on film) of the immune response, necrotic nodules and clearing through the gills etc, will scan them and do a quick outline description soon :)

Elly Jeurissen Thanks Stuart, looking forward to that :-)

Message posted on The Global Diving Community on 15 Aug 2013
Rob Durrant Really struggling to ID this little chap, only about 6mm across, found under a stone in water lower shore on a low tide at Hannafore, Looe. No doubt obvious to the more experienced! Help, please?

Rob Durrant I agree that the colouration is is often found in C. maenas, Dawn; but I didn't think so. It seemed too round, almost like C. pagurus, as were the teeth on the antero-lateral margins, not sharp enough for Shre crab. Also more hairy.

Rob Durrant Also eyes v wide apart, and seems to be 5 lobes between the eyes rather than 3.

Rob Durrant Definitely not a Hairy Crab. I know them very well, and have kept them in aquarium and have cast netting. As also Circular Crab.

Rob Durrant Chelipeds seem quite small.

Rob Durrant And now if I enlarge the upside-down image, I see the chelipeds are dark-tipped (not black), and do have lines of small tubercles like Atelecyclus rotundatus.

Andy Horton https://www.google.co.uk/search?q=Atelecyclus+undecimdentatus&rls=com.microsoft:en-US:%7Breferrer:source?%7D&rlz=1I7ADRA_en&tbm=isch&tbo=u&source=univ&sa=X&ei=rlN9Ur-BEo2QhQfcroHgAw&ved=0CEEQsAQ&biw=1024&bih=610

Andy Horton Circular Crabs have been found in shallow water over sand on Sussex shores. I have found them but not very often.

Rob Durrant Thanks, Andy. I have been looking again at the netting of a specimen I had covering three moults. and I think now that a Circular Crab is prob best fit at the moment. The pie-crust antero-lateral teeth, tubercules on dark-tipped chelipeds, hairiness, and 5 lobes between the eyes, all seem to fit.Will try to photgraph the netting tomorrow for comparison, and see what you think. I do resist the shore Crab suggestion, though. A lot there doesn't seem right to me.

Marco Faasse Rob Durrant, you wrote "almost like C. pagurus". In my opinion you can leave out the two first words ... Its juveniles are less oval, more circular, and more hairy, with teeth that are more pronounced.

Rob Durrant Thanks, Marco, but I totally disagree. We have vast numbers of C. pagurus on my local shore, and I only ever see what are clearly identifiable as miniatures of the adults. But will post more pics of specific features.

Andy Horton I think it is almost certainly Carcinus maenas, the Shore Crab, as I assume they are all the same crab.

Rob Durrant They are all the same crab, Andy.

Andy Horton Where was it found? (Circular Crabs also come across as round.)

Marco Faasse It is either Cancer or Atelecyclus. On the last page of this publication you can find drawings of juvenile Cancer with roundish carapace, relatively long antennae and 5 teeth between the eyes (however they change quickly when they grow larger): http://core.kmi.open.ac.uk/display/4503180

Rob Durrant It was upside down on the underside of a stone in water on the lower shoree on a low tide, Hannafore, near Looe, Cornwall.

Rob Durrant Very many thanks for that very helpfulresource, Marco. I've had a look at those pages and saved the paper for a better look later on. For me, now, it's Atelecyclus. Not unusual for it be difficult to securely ID juveniles in many species, I suppose, since they are often somewhat 'fluid' perhaps.

Marco Faasse Also be aware that Atelecyclus undecimdentatus that is known from the Channel is more shaped like Cancer than A. rotundatus. I don't know whether the ridges on the chelipeds are diagnostic.

Rob Durrant Thanks, Marco.

Rob Durrant Very little seems to be available online by way of images, but the shape certainly fits better, and the tubercles are there.

Gerard Heerebout Agree.

Stuart Pearce Another shot from the Tobago fieldtrip in 2006....

Ernst Andres YESSSSS <3

Stuart Pearce Thanks Ernst :)

Ernst Andres You´re welcome my friend :-)

Cameron Easton Just trying to work out when my daughter was doing her Tobago field trip. It was about then - but she was with the Old University ... Glasgow. Were you connected with our august institution Stuart - you must have been given your involvement with Millport. (I'm a Glasgow lad - BSc PhD and ongoing teaching/research for the last 30 odd years!) I feel a connection!

Shohei Shigeta Wow.

Stuart Pearce Thank you Shohei :)

Stuart Pearce Hi Cameron, no connection to Glasgow unfortunately, all linked to Hull University, we done a trip to Tobago every year because the main place there is called Scarborough, same as where our campus was based. Millport, like most UK universities we went every year, I went as an undergrad, then a further 3 times as teaching/research whilst doing my PhD. Also done 2 yrs at Bangor University in molecular biology (M.Phil), innate immunity research on Carcinus maenas & Necora puber. How is your daughter doing now, still following in the family footsteps? :)

Message posted on The Global Diving Community on 06 Sep 2013
Beccy MacDonald Hello lovely people, I am currently putting a piece of work together for some work experience students and need some photos of Carcinus maenas, Pleuronectes, Crangon crangon, Cerastodermus edule, Nereis sp. and Haematopus by tomorrow. If anyone has any that they dont mind me using could you please let me know or post them on here with permission, thanks :)

Andy Horton If you are really stuck: http://www.glaucus.org.uk/Shorecb3.jpg Permission to use for the reason stated. http://www.glaucus.org.uk/c-maenas.htm

Andy Horton Permission to use for the reason stated: http://www.glaucus.org.uk/Cockles.jpg It is the middle ones.

Andy Horton This is not very good either: http://www.glaucus.org.uk/crangon.JPG I hope somebody will reciprocate when I revise my Seashore presentation as my pictures used to be good but they are not up to scratch any more. Permission to use for the reason stated.

Andy Horton I have misplaiced my flatfish. I am sure the birders have got better Oystercatchers. And although I have got a Ragworm somewhere, it is not immediately to hand.

Andy Horton http://www.glaucus.org.uk/Shrimpers069e.jpg I am sure you would not want to use this one! I was behind the camera.

Andy Horton Permission to use this one. http://www.glaucus.org.uk/Crangon025.jpg My project for next issue is to get a decent picture of a shrimp.

Beccy MacDonald Thank you so much Andy, and also to Paula Lightfoot :)

Vinh Lam Anyone know what this guy is? It was coughed up by a Tub Gurnard I caught off Brighton. I'm guessing it's an immature of one of the swimming crabs (Portunidae) looking at it's back legs but which species?

Andy Rapson Liocarcinus vernalis?

Andy Horton Carcinus maenas or Liocarcinus vernalis.

Andy Horton http://www.glaucus.org.uk/c-maenas.htm I might even favour the Shore Crab.

Andy Rapson The rear pair of legs look to flattened to me for it to be Carcinus maenas. I've been looking through some books and it does seem to match Liocarcinus marmoreus fairly closely but I'm not really familiar with that species so it makes it more difficult to tell.

Vinh Lam I agree, none of the photos I have of similar sized Shore Crab have as rounded real legs as this one. Also the second last segment is pretty rounded and not seen on any of my shore crabs either. I would say that it is a Liocarcinus but which one?

Gareth Horton Found the first weever fish of the year off Shoreham/wide water. Seems quite early. And quite painful!!

Andy Horton Hearsay or personal experience? http://www.glaucus.org.uk/weever2.htm The pain. Describe in detail for the records please and how the unfortunate fish was trodden on!

David Wilson Two of my 3 children have been stung. Matt was sorting through a shrimp net at Salcombe and was stung on the thumb. Sophie jumped over the side of the boat at Shell Bay, Studland straight on to a weaver. Bathing the area in water as hot as you can bear and anti-histamines help.

Andy Horton Over 40 degrees C, which I think is half boiling water and half tepid water

Gareth Horton Thought I'd replied earlier so apologies. 2.5 feet of water and paddling with the dogs east of the wide water Shoreham. Just caught the ball of my foot behind my left big toe. Was much like stepping on glass or sharp mollusc. Pain was 6/10 for 45 minutes then subsided with waves of soreness all day. First sting for twenty odd years so not bad for a bloke in the sea nearly everyday. Risks are low clearly but glad it was me and not dogs or young son!

Andy Horton One of the BMLSS members did the science on temps. I translated it by sticking the thermometer in a cuppa tea.

Ronald Surgenor Heres a link to one of my weaver fish photos, they can be handled with care and touch wood I haven't been stung yet!! a guy gave a tip of warming a damp towel on the engine block of a boat/car to wrap around the stung area until you get access to proper medical treatment. http://www.flickr.com/photos/ronaldsurgenor/4920060501/

Andy Horton That looks like a large one. Weevers have fierce razor teeth and its lucky they are not bigger as they could do some damage and make the Jaws teeth look tame. Also biting parasites. Deaths are very rare.

Huan Tan They taste good.

Andy Horton Greater Weever seen on the fishmonger's slab

Andy Horton George D Moffat: off Sussex, local boats, not many.

Douglas Herdson Greater Weever also gets caught off Devon and especially Cornwall. Not often landed, but occasional quarter boxes, presumably go for fish soup.

Andy Horton One or two reports indicate the Greater Weever may have a greater sting: (Quote) I was stung on the tip of my right index finger by a Greater Weever three years ago in Tenerife. After spending four days in the local hospital in intense pain, with my whole arm swollen to the size of my thigh, I have lost the use of this finger: I cannot bend it nor straighten it, it is always cold to the touch and any slight scratches take five to six weeks to heal. (Alan Brady). This could be another species though ??? Scorpion Fish species comes to mind. NB: Lesser Weever stings can have the effects of being unable to move toes.

Andy Horton weever | wiv | n. E17. [Perh. transf. use of OFr. wivre serpent, dragon, var. of guivre f. L vipera VIPER.] More fully weever-fish. Any of various elongated NE Atlantic fishes of the genus Trachinus and family Trachinidae, which lie half buried in sand and have venomous dorsal and opercular spines with which they can inflict painful wounds; esp. (more fully lesser weever) T. vipera, which is common along European and Mediterranean coasts (also called viperfish). Also (Austral.), any of various sand perches of the family Mugiloididae. --------------------------------------------------------- Excerpted from The Oxford Interactive Encyclopedia Developed by The Learning Company, Inc.

Andy Horton Echiichthys vipera http://www.fishbase.org/Summary/SpeciesSummary.php?ID=1364 PS: Going shrimping this morning

Penny Martin enjoy the shrimping ... you are up early !!

Andy Horton I could not get to sleep.

Andy Horton Ideal shrimping conditions, but just an average shrimp haul. Two small Weevers but not much else and no Slipper Soles (which is unusual).

Andy Horton 28 May 2012 A special shrimping trip to Lancing Beach (by Widewater) (with Dudley, & others) in ideal weather conditions (1.5 metre neap low tide) caught three pints of Brown Shrimps, Crangon crangon,between us, but there was not much else in the nets: frequent flatfish fry, two small Lesser Weever, Echiichthys vipera, one swimming crab Portumnus latipes with "fleur-de lis" markings, one Vernal Crab, Liocarcinus vernalis, one badly damaged (but still alive, it nipped me) Masked Crab, Corystes cassivelaunus, a few large green Shore Crabs, Carcinus maenas, and a small Plaice, Pleuronectes platessa, (or possibly a Flounder?).

Penny Martin

Penny Martin could anyone help ID this crab ... found by a friend of mine in Orkn. Thanks

Christian Skauge You haven't? This is a very common colour in Norway... for dead crabs of the Carcinus maenas crab. Was this one alive? I would not think so...

David Wilson I've seen dead shore crabs this colour.

Andy Horton Sometimes, I find large green ones. http://www.glaucus.org.uk/c-maenas.htm I have not got a photograph on my computer. I expect there is one on a slide somewhere.

Chris Barrett I've read that the colour of Carcinus varies according to their diet

Christian Skauge It does, we se 'em green, reddish, sometimes even blueish.

Penny Martin I've never seen a blue one here before lots of green and brown ... will keep a look out ... i wonder what it could be eating that is different ??

Penny Martin Thank you ..... feel a bit dense but my books mention shore crabs being greens and browns. I will see if blue ones are often found around Orkney ....

Andy Horton I would like to see a clear photograph of a large bright green one please. Not a dull green on, I've got plenty of those.

Darryl Mayer Is the blue crab not just sun bleached?

Andy Horton Please measure the very large ones that you discover. Maximum quoted size = 86 mm carapace breadth [which doesn't sound very big to me, 3.4" in imperial units - Pete], but usually less. Terminal ecdysis can be any time from ~60 mm. (from 'Biology of the Shore Crab'). Anything over 100 mm ??? Is there any reason why they do not grow this big?

Andy Horton Also local names for the Shore Crab please?

Andy Horton What do they actually eat from first hand experience in the wild please? Polychaete worms are often seen in their mandibles and claws. In captivity they will eat virtually anything. I think they have trouble with Dogwhelks though. Virtually anything smaller than them, not Lobsters.

Penny Martin In Orkney in May??? ..... I don't really think so

Christian Skauge Iv'e seen them take on razor shells (Solenidae sp.).

Andy Horton In Sussex they migrate up estuaries with June being the peak month at the mouth of the rivers: Adur, Ouse, Arun.

Chris Barrett Never looked at crab diet, but I think littorinids are a high contributor

Andy Horton Crothers has got the diet list in his book, but I have mislaid my copy, being a this pamphlet type book and not where it should be (last night). My observations indicate polychaete worms with littorinids only a small proportion as the crab is not particularly well named and the Shore Crab is only a book name anyway. Local names are falling out of use.

Animalia (Kingdom)
  Arthropoda (Phylum)
    Crustacea (Subphylum)
      Malacostraca (Class)
        Eumalacostraca (Subclass)
          Eucarida (Superorder)
            Decapoda (Order)
              Pleocyemata (Suborder)
                Brachyura (Infraorder)
                  Eubrachyura (Section)
                    Heterotremata (Subsection)
                      Portunoidea (Superfamily)
                        Portunidae (Family)
                          Carcininae (Subfamily)
                            Carcinus (Genus)
                              Carcinus maenas (Species)
Associated Species