Young Grey Seal (Halichoerus grypus). Nostrils are the key to ID

Thanks to Bob Davison for this picture of a young grey seal (above).  One of the best ways to tell a young Grey seal from a Common seal (Phoca vitulina) is to look at its nostrils.  The Greys have nostrils that are kind of parallel, whereas those of the common are much more V-shaped and almost meet at the bottom (below).

However, that's all very well if you have an obliging seal that does not mind having its nasal appendages examined in some detail.  This is not always that easy to do.  As usual with these little identification issues, it is always easy to tell a common seal from a grey seal when you are in the pub, but it is not always quite so easy when you are in the field...  Full adults are less of a problem - the greys are much bigger for a start....  Well, usually....

Seals can of course 'seal' their nostrils while underwater.  They can also sleep while holding themselves vertically in the water with their heads above the surface - but only for around 90 seconds at a time...