Tag Archives: crabs

Crab tide

Yesterday’s tide line on Penrhos beach comprised almost nothing but spiny spider crabs, hundreds, probably thousands of them. It looked like crabageddon.


Spiny spider crab shells

In fact, I am assured that these aren’t actually dead crabs, they are just the shells from the annual moult. Which explains why there were no birds taking any interest and no smells either. Somewhere out to sea there will be thousands of naked spiny spider crabs waiting for their new shells to grow.

I was puzzled how the crabs could manage to shed their shells, whilst seeming to leave the shells intact. How was that possible? Then it was explained to me that the shell can hinge open (hinging at the front) and the crab wriggles out the rear.  Once I knew that, I had to go and check it out for myself.


Here’s a freshly washed up crab shell. You can tell it’s empty by giving it a tap and it sounds hollow.


And, sure enough, if you lift the back edge of the shell, it easily opens up to show you the empty space inside:)


I also spotted this “jellied” crab…




Spiny spider crabs – Maja squinado

Spiny spider crab - Maja squinado on Llanddwyn beach

Spiny spider crab – Maja squinado on Llanddwyn beach

For some reason, there were quite a few of these large spider crabs washed up on the beach this morning. Most of them were slightly alive, but only slightly. It’s common to see shells of the crabs, but much less common to see so many live and intact crabs. However, the gulls were having a field day, so soon these big crabs will probably just be shells and scattered claws too :(

spiny spider crab2