Nick Upton's picture

Common limpets?

Observed: 20th August 2012 By: Nick UptonNick Upton’s reputation in InvertebratesNick Upton’s reputation in InvertebratesNick Upton’s reputation in InvertebratesNick Upton’s reputation in Invertebrates
Two Common limpets (Patella vulgata) attached to rocks exposed at low tide, near Falmouth, Cornwall, UK, August.
Common limpet (Patella vulagata) underside.

I thought these smallish Cornish limpets c 3cm might be Black-footed at first as they were more flattened than common usually are, and had apexes off center and 2 ridges visible at the rear end, but the underside shows some tortoiseshell colours and not the black and white stripes and squared off rear end of black-footed (foot colour could be either..), so I think they are young P. vulgata, Found low on the shore under a boulder, and P. depressa prefers exposed sunlit sites I believe

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dejayM's picture

No doubt

Another old post. I am here because I am researching for my own Patella post. People will be scared to agree here because of the shell markings and the very shallow profiles..
Like you, I think it is vulgata BUT the fine ridges and low profile are confusing. I agreed, then changed my mind!
My recent study suggest a fairly square end to depressa
But then there's - Patella ulyssiponensis, Patella intermedia etc.!
Going forward from here shows the short range of shapes but it is NOT conclusive.

Nick Upton's picture

Mystery limpets

Many thanks for your comments. If you ever become sure on these, do confirm or change the ID! I suspect they'll remain "can't be sure". Just shows his tricky firm IDs can be at times. I think I ruled out ulyssiponensis at the time on interior shell colour, but looking again at online"IDs" (which could be be wrong) it seems it can be tortoiseshell not always the nacreous white that Marlin and other references describe, but I'd need to know how firm those ID were and the realistic range of colours for that species to consider that. This link I just found is intriguing though - suggestion the variation is wide, and the external ridges and asymmetry fit…. so maybe that's a realistic ID;

intermedia is I think a synonym for depress, unless they've mow been separated.

Nick Upton, naturalist and photographer.

dejayM's picture

Coming back

Ordinarily and not long ago I would have agreed to Common limpet. But they are really quite difficult to tell apart via just a top-view. Personally I would rather see these titled Limpet but with notes suggesting that they might be one of, perhaps, three.
I have been through this several times with an expert, including having empty shells to hand, to the conclusion that it really IS hard to tell them apart unless one can see the animal or at least the underside - which usually means killing it.
That it is common and that other examples can be seen as close lookalike, is no proper evidence. This is really VERY unfortunate.
I feel like a spoilsport because I have agreed to a few Commons in my quite short time here - though there probably is no harm in that..
I have read and read, talked to experts, posted a few and STILL believe it might be impossible to tell.
There are a good number of limpet Observations, is one of mine. Despite me making it easy for people to agree, there are still none.
And here is my only slightly more educated post in which I have written -

"It is very difficult to find definitive information which allows correct separation of the three most common ones and a huge overlap in descriptions of each. Book illustrations are somewhat vague and the internet is loaded with pictures which do nothing for separation."
Jan Light's "straightforward" Guide is here She writes "With practice it is possible to discern these differences and make accurate judgements based on exterior appearance but it is not foolproof even for the ‘experts’" Oh dear then!

Nick Upton's picture


Just back off hols. Makes one wonder how many seashore surveys of various kinds misidentify Limpets of various kinds / how under-reported the rarer species may be. N

Nick Upton, naturalist and photographer.

dejayM's picture


Yes, I came 'a cropper' recently when I talked to an expert researcher, with examples (of shells) to hand. He was in no doubt that it was nearly impossible to tell from shell alone, even when the insides were quite fresh. I wonder if THEY know their names.

ChrisMcA's picture

The problem of the Patellas

I believe Nick's 2nd photo's sufficient to show it's vulgata. based on & other descriptions its greyish yellow foot isn't dark enough to be a depressa (& no sign of the white tentacles), Plus ulyssiponensis "lacks any grey shades"
At least they don't hybridise according to
NB Dejay, your glaucus link implies you can 'flip the unwary limpet over with a knife' & after are 'best replaced on their mscle scars'

dejayM's picture


Yes, I agree, these are most likely to be vulgata. And yes, I suspect Jan Light may well regret writing that. Finding unwary limpets is not very difficult and even a credit card will do the trick. But I have watched them on return to their scar - they are generally very uncomfortable. To prise them off at upper shore levels will often mean them losing all their muscle adhesive powers and their very high internal moisture level - in sunshine that would always be devastating. At lower shore levels they will usually get washed from their new purchase the moment moving water comes.
The mortality level of limpets is astounding (judging by the number of empty shells), considering how much energy they put into their survival strategy.