I spent an enjoyable half an hour watching a juvenile gannet fishing just off-shore today. You know the routine I'm sure....glide about a bit on your long narrow wings looking for a decent fish, then jink and start the dive, pulling your wings in and back until they form a point behind you and then....hit the water like an arrow. Choomph..straight in.
I use the memory of the pain I felt last time I did a belly-flopper dive into the swimming pool from a couple of feet up as a measure of just how much damage potential there is in hitting the water from gannet height.
Unlike me of course gannets have evolved to do this and unlike me, nothing sticks out as they pierce the water surface.
The first thing that strikes you when you look at a gannet's skull is just how steamlined it is - whichever way you view it. From above, the beautiful smooth sweeping lines are very noticeable but from the side too everything is wonderfully sleek, guaranteeing the smoothest possible entry.
There is a one further trick. Examine the forehead closely and you can see that the front of the skull is reinforced with extra thick bone forming a protective plate.
In spite of all of this....I do still wonder if gannets ever get headaches.