Light reading

While walking on the beach at Longniddry I found this vacated limpet shell, and it struck me that it was quite a bit larger than any I'd seen before.  And it seems it is indeed a bit of a corker.

I didn't know until today that they can live for 15 or 20 years, and I had supposed that you might simply count growth rings like a tree.  I proceeded to read far too much of a Ph.D thesis with the catchy title of "The population dynamics of Patella vulgata and other limpets" which explains that you can't really count growth rings because they correspond to age, availability of forage and degree of shelter on the shoreline.

I can however use my vernier calipers and reveal that its 68mm length puts it substantially beyond any specimens in the four groups studied by Mr W Ballantine in 1960.  Its 35mm height gives a relative shell height of 51% which puts it fairly well into the 12+ year age range.  I counted 16 growth rings anyway before the smooth topmost part, so I think this was a pretty elderly female limpet when she fell off the rocks and got picked clean by the birds.