dejayM's picture

Icelandic cyprine

Observed: 9th June 2013 By: dejayM
Biological Recording In ScotlandHighland Biological Recording GroupOrkney Biodiversity Records Centre
dejayM’s reputation in InvertebratesdejayM’s reputation in InvertebratesdejayM’s reputation in InvertebratesdejayM’s reputation in Invertebrates
tooth slot

A hoard of shells, all found in one foray. The biggest 103mm - an incomplete broken one was larger - maybe 124mm.
Elsewhere in iSpot this is called an Ocean Quahog - a good and acceptable alternative name.
>>WoRMS name<<
linked to
See Comments below.

Species interactions

No interactions present.


dejayM's picture

The hoard

Origin 10 June 2013
A collection from a grey seal haulout. I am not quite certain whether they bring these ashore to crunch at leisure or whether the shells are simply washed to this place.
However they are really large, heavy, thick, tough and robust shells, so weather and wave bashing is not likley to have the same effect as I saw - some were in quite small pieces.
This shells are not as common as books might have you believe - I consider them quite rare and a treat to find.
Some key features that helped me decide -
...wonderfully strong umbo or beak - Picture 1
..the teeth (Pictures 2 and 3), single one side, twin the other. Like a peg and slot really and clearly mentioned as 'prominent cardinal teeth' in all ID texts. The dentition is more complex than my simplification.
.. the thick periostraticum (Picture 4)
..the annual growth rings (picture 5) usually many hundreds; in one here, there may be over 500, though recent records suggest it ought be less than 450 (just under 500 years old then).
For those who might like the challenge - view Picture 5 original. The line is a fraction under 10mm - the shell is nearly 110mm. The annual growth rings are spaced fairly evenly across the whole shell. Like in a tree, there might be summer and winter marks. Try the math.
An update here >>National Geographic<<
See my other post for more information

JoC's picture

30 ridges in 10mm,

so a tiddler when Isaac Newton's derivation of Kepler's laws from his theory of gravity, contained in the paper De motu corporum in gyrum, is read to the Royal Society by Edmund Halley?


Amadan's picture

Wow -

This really brings home to me my ignorance of marine life in general, and the molluscs in particular. I'm quite a way from the sea now, and realise I should have spent more time on the shore when I lived just a few miles away.
A really fascinating post.

dejayM's picture

me too

I have been here, in iSpot, for 24 short weeks. During that time I have put up many marine posts. Whilst a good Naturalist and fair photographer, I am a novice at Marine Biology.
There are few, VERY few, TOO few people responding to marine posts, but those who do have urged me on and I have learned a great deal - it is what I came for.
You are right of course - fascinating.
Thanks for the Wow Amadán (surely you aren't)!

the naturalist man's picture

Seal shells

Interesting question, I've never noticed seals bringing anything ashore to eat and I've spent many hours watching seal pupping beaches and haul-outs.

However, that does not mean it could be a localised learnt trait. Most likely, they are finding the shells just off shore and eating them in situ; being close to the haul-out beach the empty shells are washed up there.

Graham Banwell

Visit the iSpot Yorkshire forum for information on events, issues and news relating to 'God's own country'

dejayM's picture


Yes, Graham. I'd agree with all that. Quite unexpected, my find and inexplicable.
I have been close to the haul-out a number of times - there are up to 50 greys there occasionally. It is a wild and pretty remote place, visited by few people. This suggests that it is 'home' to those seal. Like you I am sceptical about the idea of them bringing anything ashore for snacking. Your suggestion that they may locate them nearby, smash them to eat and leaving bits to wash ashore is slightly flawed by them looking so fresh and untumbled. (I have added another picture)
Some of these cyprines were really pretty broken up and, interestingly the hinges of some still intact. The shells are several mm (up to 6mm) thick, much thicker than most other shells.
The whole shell-sides and the bits had not been washed around much; the edges are sharp (still) and a few joints intact (as I said); I left behind many other pieces. It is as though someone with a hammer may have visited. But that is quite unlikely.
Bigger birds, like G-Blackback, maybe Skua, even Raven could do this by the 'bombing' technique (it is very rock strewn in places).
So we are left with a mystery, one that I cannot solve, nor investigate further, without revisiting. When I do, and if I find more of the same, then we might need to discuss further.
I thank you for your interest.

the naturalist man's picture

Eating shellfish

They certainly look broken rather than bitten, I'd expect some sign of teeth marks. Your idea of birds sounds very plausible.

Keep us informed if you discover more.

Graham Banwell

Visit the iSpot Yorkshire forum for information on events, issues and news relating to 'God's own country'

dejayM's picture


Graham - more has happened since this post.
Yes, I have watched gulls lift and carry other shells to drop them on rocks - well recorded behaviour. So, greater black-backs could do this in my 'remote' place (ideal terrain).
However it is rare for a complete animal to be found on any shore.
So, it has also occurred to me that otter may bring them ashore - certainly if they are plentiful (the shells) as even only one otter could do this. They have quite powerful jaws but, again, as you say, no teeth marks.
I am about to put up another observation about Quahogs but meantime watch this

dejayM's picture


Thanks for your vote Chris - some things take a LONG time to get around.
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