Tag Archives: spiny spider 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.

spidercrabmoult0712b

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.

spidercrabshell

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

emptyspidercrabshell

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

jelliedcrab

I also spotted this “jellied” crab…