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Metridium senile

(Linnaeus, 1761)


Andy Horton This one is a difficult species. I would identify the anemone in the photograph as Metridium senile.

Andy Horton I think they are the same species

Darryl Mayer I wouldn't. Plumose anemones' tentacles are much finer and in many more numbers than the above picture. They are also shorter in length being "part" of the outer casing of the animal. Effectively in the plumose, it's the whole body wall that retracts not simply the feeding tentacles themselves that retract.

Andy Horton Basal laceration is clear.

Message posted on NE Atlantic Cnidaria on 13 Mar 2012
Andy Horton Metridium senile with offspring seen being reproduced by basal laceration

Message posted on NE Atlantic Cnidaria on 13 Mar 2012
Jan Roar Gjersvold Metridium Senile

Tom Hobock Way Cool Great Photo

Jan Roar Gjersvold Thanks Tom :)

Ilse Merz beautiful

Jan Roar Gjersvold Thanks alot for nice comment :)

Ernst Andres Wonderful (Y)

Antonio Colacino Very nice shot, North sea?

Jan Roar Gjersvold Thanks a lot mate :) This shot is taken at Hitra / Norway

Message posted on The Global Diving Community on 17 Aug 2013
Kåre Telnes Does anyone recognise this species? The picture is taken today in Norway, at 15 meters depth, on a rocky, current exposed location. The height of the cylinder is approximately 1 cm.

Marco Faasse Metridium senile var. pallidus

Kåre Telnes Are you sure? It looks a bit different from the M. senile I am used to see. It seems to have fewer arms and shorter cylinder, relative to the diameter.

Kåre Telnes Yes, I agree, but it is difficult to see which one.

Marco Faasse Those characters are typical for the var. pallidus Kåre Telnes

Marco Faasse The collar suggests Metridium

Erling Svensen I agree with Marco. This one grows only to 2-3 cm, and we have a lot in exposed localities.

Kåre Telnes Ok, then I learned something new today, as well. Thanks!

Kåre Telnes I see some sources claim that the two morphs pallidus and the larger dianthus are caused by different enviromental conditions. This is a bit strange since i

Kåre Telnes ... saw many dianthus on the same location as the pallidus above.

Marco Faasse Really difficult to tell apart are var. pallidus and small var. dianthus, produced by basal laceration of bigger specimens ...

Andy Horton Interesting. I do not recall a sea anemone anything like this one. But that could be my memory. Diadumene is possible ??

Andy Horton I would say this anemone is not recorded. New species? It is so far apart from any I have seen for real or in photographs. At least I would rule out Sagartia and Metridium quite quickly.

Kåre Telnes Do you have any similar images, Erling Svensen? I could not find any on UWPHOTO.no.

Erling Svensen Kåre, I have hundreds. This anemone is very, very common in Egersund. When diving exposed localities, it is very common.

Message posted on NE Atlantic Cnidaria on 13 Jun 2013
Andy Horton This anemone was not recognised at a a Coelenterate Society meeting years ago at the NHM.

Andy Horton Any takers to ID this one? I know what it is though.

Marco Faasse Metridium senile, no doubt about it.

Andy Horton Yep. Was it that easy?

Marco Faasse Yes, easy enough. I was sure you had the same opinion. The best way to get to know the different shapes of our common sea anemone species is to observe them for a long time in captivity.

Message posted on NE Atlantic Cnidaria on 13 Mar 2012
Penny Martin Are these metridium pallidus ?

Erling Svensen What is the different between M. senile and M. pallidus? We have many "small" M. senile - very exposed. Could that be pallidus?

Wilfried Bay-Nouailhat young Metridium senile we see in Brittany look like that. I think M. pallidus is smaller.

Penny Martin according to Chris Woods book ... "P does not exceed 25mm across, disc is flatter notwaed as in larger variety and not usually more than 200 tentacles. column shorter not any taller than wide. It is not clear whether the 2 forms are distinct varieties or variants resulting from different environmental conditions"

Andy Horton I think pallidus is just a variant rather than a species? I might have some photographs. In poor environmental conditions M senile reproduces by basal laceration leaving lots of tiny sea anemones.

Penny Martin * not waved

Penny Martin Bucklin (1985) investigated biochemical genetic variation and concluded the presence of two morphs of Metridium senile but that they were variants resulting from different environmental conditions and were not taxonomically distinct and therefore not 'varieties' as described in many texts.

Message posted on NE Atlantic Cnidaria on 12 Mar 2012
Erling Svensen This - I think - is the same anemone as Kåres below. The Metridium senile var. pallidus. We have them exposed and in many different colour variations. Growing only to 3 cm.

Kåre Telnes As you know, I am just a happy amateur, and really don't have a clue. Still, I cannot help thinking that these look a bit different. They seem to have far more tentacles than "mine". "Mine" has less than 50 which is correctly less than the 200 pallidus is supposed to have. Do you have any images of a pallidus with this few tentacles?

Erling Svensen What about Diadumene sincta? I do not have so many pictures at my work - so I look when coming home. But the D. sinctra is an anemone that is also quite common in Norway and look quite like Kåres below.

Kåre Telnes I should leave this to the experts, but could not help myself. I googled Diadumene cincta and the juveniles I found images of, had a very different, vase-shaped cylinder and far more tentacles.

Erling Svensen Fine, Kåre. Looke at the 3 last images.

Erling Svensen Have seen Bernard Picton Habitas pages? http://www.habitas.org.uk/marinelife/photo.asp?item=diacin

Message posted on NE Atlantic Cnidaria on 14 Jun 2013
Erling Svensen Do anybody know why this Sagarthia elegans anemone have a couple of very long arms? The anemone is only 1,5 cm across the disk.

Andy Horton The tentacles enlarge and subject of my talks at the Coelenterate Society and probably Porcupine Society talk way back in the past (20th century). It was on Sagartia troglodytes.

Andy Horton Feeding As many as five large 'catch tentacles' seem to be enlarged versions of existing tentacles, and these can be best observed in aquaria. They are usually translucent. In the wild, this anemone is known to eat shrimps and small crabs that are 75% of the bulk of the anemone, and these tentacles would be necessary to manoeuvre the prey to the mouth. They will actively search the surrounding water for prey of mostly small crustaceans. Catch tentacles are controversial in a number of ways: 1) They are recorded as not existing in preserved specimens in species like the Plumose, Metridium senile, in which they are actually quite common. This is because they are not separate tentacles. http://www.glaucus.org.uk/S-troglo2.htm Pictures are still on the old slides and have not been copied.

Erling Svensen Thanks Andy. Very informable and I did not know. Very nice to observe and learn new things.

Andy Horton These are my anecdotal observations and conclusions from the evidence. In 1993 it was new.

Ron Ates Nice picture. These elongated tentacles have been seen on several more species of acontiarian sea anemones. In S. elegans since at least 1860 or so. They are called fighting tentacles (previously catch tentacles) for their ability to damage neighbouring sea anemones and other animals.

Andy Horton I tested the this "fighting bit" in both Sagartia troglodytes and M. senile by putting the sea anemones next to each other. The tentacles did not enlarge. I put live food in the water and tentacles cames out to try and catch the food. In Actinia equina the acrorhagi seem to be used for fighting, or possible the tentacles do the opposite and retract when they bump into each other. Best results occur when Actinia is matched up against an Anemonia Snakelocks. I repeated the feeding experiment about a hundred times. The catch tentacles did not always appear but they did at least a dozen times out of a hundred, possible more. In eh Beadlet, Actinia the tentacles retract most readily but also in M. senile and the A viridis as well.

Ron Ates Hi Andy,

Ron Ates Hi Andy,

Ron Ates Hi Andy, you raise interesting points, let's compare notes. I am new to this facebookstuff, sorry for that. Things may go wrong as I must learn. I agree that the evidence can be tricky. For instance Diadumene cincta, which is very common in the Netherlands shows fighting tentacles all the time. Yet I have never seen aggressive interactions with other anemones. However, Manuel (1981:122) witnessed it in a fight with Anemonia viridis (your snakelocks) and the latter was killed. So I conclude that elongated tentacles may kill competitors. Another thing that seems to be clear from the literature is that food never adheres to these elongated tentacles. Would you like me to send you pdf's of what I have on this subject?

George Brown Welcome to facebook Ron. Your pdf's sound interesting.

Andy Horton Yes please. There is a files section that *.pdf files can be uploaded to. I don't think I have seen Sagartia actually eat at all. I have seen them spit out tiny Shore Crabs. More later.

Ron Ates Please see Purcell (1977) for an account of fighting tentacle behaviour in the plumose anemone Metridium senile. Food does not adhere to them. They are used in aggression. As far as Sagartia elegans is concerned I have seen it damage and chase away snakelock anemones in my aquarium. Admittedly, in other species the function of elongated tentacles is not always as clear. I will now try to upload part of Purcell (1977), keep your fingers crossed.

Andy Horton The main function of my observations was that they were elongated tentacles rather than separate tentacles.Then there was how to induce the sea anemones to eat which was achieved by introducing food to the water &/or fresh sea water and it was then that the tentacles were observed. When tentacles of other sea anemones meet each other I observed retraction more often than not.

Message posted on NE Atlantic Cnidaria on 24 Sep 2013
Andy Horton This is an interesting and sometime hard to identify species: http://www.marlin.ac.uk/speciesinformation.php?speciesID=3149 Does anybody find this small sea anemone? Diadumene cincta

Erling Svensen I see it in South West Norway. I agree it is very dIfficult to identify.

Sarah Bowen Yes, we've seen it in the Cleddau Estuary, Pembrokeshire. Pretty little thing that can be confused with baby Metridium senile!

Andy Horton Sarah: I had the same ID problems.

Penny Martin me too .... I'll post a photo ... not sure if it is Metridium pallidus ??

Message posted on NE Atlantic Cnidaria on 12 Mar 2012
Andy Horton Eelpout

Paula Lightfoot Zoarces viviparus

Andy Horton I have never seen one of these for real on the shore or in an aquarium.

David Wilson I used to find these in the Thames estuary near Southend in winter, Mostly the smaller males but occasionally large pregnant females. I think that was the southern limit of their range.

Andy Horton David Wilson: what time of the year were they found please?

David Wilson I think it was January through to March but I'm uncertain of the exact details. Look around the piles of the pier about two thirds of the way to the end. There were also lots of fan worms and metridium senile. They

Vinh Lam I've never seen them while rockpooling, but have seen them in public aquariums. Just uploaded some pictures onto my flickr here http://www.flickr.com/photos/puffinbytes/tags/spb:id=01KY

David Wilson The males I found were small, perhaps about 10cm but the female was about 30cm and very pregnant.

Andy Horton As a cold water fish, so self respecting Eelpout would be found between the tides in this weather. That is winter rockpooling.

David Fenwick Snr Could this be Stomphia coccinea, a pity it didn't open I know. Found attached to the underside of a rock at Marazion yesterday. It's not a species I'm familiar with.

David Fenwick Snr I should have said, about 25mm, or maybe a little more in diameter.

Andy Horton Odds on it is Sagartia elegans

Andy Horton I do not know about the dots on the stalk. The second unlikely possibility is Metridium senile.

Andy Horton Note the acontia

David Fenwick Snr Re. the 10m and below, the site at Marazion is 'extremely' sheltered and there are all sorts of things you'd not expect intertidally. Area probably best treated as a lagoon with full salinity. By the way, just got back from pooling; found my first cup corals. YIPEE.

Andy Horton Marazion is the best shore I have been to and that was in October. Not the best for sea anemones though.

David Fenwick Snr Thousands of Snakelocks, but with Gems, Beadlets, a few Red Speckled and the odd Daisy, Dahlia and Strawberry.

Andy Horton Ironic that as I thought it was a Sagartia. I have seen Snakelocks proliferation destroy a shore for interest. Notably, Hope's Nose, south Devon.

Richard Girdler

David Kipling Tentacle?

Richard Girdler Quite a bit longer than the other tenticles

Rob Spray Is it a defensive acontia - a really stingy tentacle?

Andy Horton It is an ordinary tentacle enlarging itself in Sagartia troglodytes. Best picture I have seen of this. http://www.glaucus.org.uk/S-troglo2.htm They could be called "catch tentacles".

Andy Horton As many as five large 'catch tentacles' seem to be enlarged versions of existing tentacles, and these can be best observed in aquaria. They are usually translucent. In the wild, this anemone is known to eat shrimps and small crabs that are 75% of the bulk of the anemone, and these tentacles would be necessary to manoeuvre the prey to the mouth. They will actively search the surrounding water for prey of mostly small crustaceans. Catch tentacles are controversial in a number of ways: 1) They are recorded as not existing in preserved specimens in species like the Plumose, Metridium senile, in which they are actually quite common. This is because they are not separate tentacles. Pic to be included 2) American research in different species of sea anemone attempted to prove that these 'catch tentacles' were used in territorial warfare between species of the same anemone to ensure spacing. In the wild Sagartia troglodytes will be found at least an anemones width away from other anemones. Aquarium experiments to try and induce the 'catch tentacles' to appear - not a predictable task - but I have managed this by introducing live Artemia brine shrimp into the aquaria and this stimulated the 'catch tentacles' to search the surrounding water for nutrition.

Andy Horton PS: Can I include your picture on the web page with the appropriate credits please?

Richard Girdler Crack on andy :) thanks for that info

Message posted on Seasearch Identifications on 28 Jul 2013
Taxonomy
Animalia (Kingdom)
  Cnidaria (Phylum)
    Anthozoa (Class)
      Hexacorallia (Subclass)
        Actiniaria (Order)
          Actiniaria incertae sedis (Superfamily)
            Metridiidae (Family)
              Metridium (Genus)
                Metridium senile (Species)
Associated Species