David Jardine's picture

'Flouresecent' Orange Red seaweed

Observed: 3rd January 2013 By: David JardineDavid Jardine’s reputation in PlantsDavid Jardine’s reputation in PlantsDavid Jardine’s reputation in Plants

This orange red seaweed was found washed ashore - fronds were <1mm in width, and the whole weed was c10cm in length, stipe dark.

Species interactions

No interactions present.


scubamann's picture


hello. Can you describe the texture; cartilaginous (firmly soft) or stiff and chalky (coralline) or soft/fluffy [it does not look it]. Any trace of the holdfast and size?
Of course the colour may have bleached in the sun.
Very tentative id might be Common Coral weed

David Jardine's picture


Thanks - it was firmly soft. the holdfast was short (2-4cm), dark brown to black and <1cm in width. With the weather we have had on the west coast of Scotland in the last few weeks I don't think it would be bleached! However, I wodnered if it might have been young growth.

Will try to move to plants

All the best

scubamann's picture

seaweed, P.S.

I think this should be in the Plants group.
From there you might get more input.

David Jardine's picture

Now done

Further photo showing stipe and holdfast added - apologies re focus on this one

JoC's picture

Epiphytic coralline red seaweed

I think the dark purple seaweed is the support on which this finely branched coralline red seaweed is growing. Or was growing, as the orange colour may represent decay. The epiphytic habit and the ball-like tufts suggest Jania rubens; if it is this, the branches will be segmented and dichotomous. If you still have the specimen, you could google images for Jania to see drawings of the branching pattern. If the branches are opposite to pinnately branched, then it is more likely to be Corallina which can be epiphytic but is more commonly found on rock.


David Jardine's picture


Sorry - specimen not kept. But checking google for Jania and also checking photos it does not appear segmented and dichotomous and the branches are opposite so looks like Corallina. Many thanks to all.

PaulBrazier's picture

Laurencia / Osmundea genus

This is definitely one of the Osmundea's. It is growing epiphytic on a Chondrus crispus (dark stipe), will be cartilaginous, but not coralline. Tentative ID as Osmundea obtusa, although there is possible confusion with Chondria dasyphylla, needing microscopic examination to confirm. Not sure whether both species are found as far north as Isle of Gigha?

Paul Brazier

lulu0705's picture

Why it isn't a coralline species.

The stiff, branched, erect and pinnate fronds of Corallina officinalis only grow to about 7 cm long, arising from a basal crust. Branches are flattened in one plane and feather-shaped. The fronds comprise chalky segments (like bones of a finger), with 3 terminal segments at the tip of the frond. This is a very common species on our shores and looks like a pink feather skeleton. The segments are very clear to see even in small specimens (v. unlikely to find a 10 cm frond) and you are most likely to find it in rockpools and not intact, washed up the shore.

dejayM's picture

Coming back

Origin 11 Feb 2014

Lucy (lulu0705). I agree with your synopsis but not quite yet with the ID (I think I might)
My Coraline here
http://www.ispotnature.org/node/314931 rather supports your description (above) and undermines Graham's (gramandy) ID, which is why there are no agreements there.

I have tried to move it on. I think even Graham might concede that he could be wrong. Surely there should be some evidence for the apparent articulation so obvious in C.officianalis? I really agree that this is likely to be Laurencia/Osmundea. But at the moment I am not powerful enough to shift likely. I think both Paul and Lucy have left the area - a shame.
Obviously there should be more debate but I think a priority could be to shift likely away from Corallina officinalis.
PS (even later)
Graham has added his agreement - thanks. But, as it is the ONLY one in iSpot, it has no Other Obs. perhaps we need not pursue this further, and then when someone else posts a Laurencia we can move back (or ON!). I remain interested because of these