Crustacea are some of my favourite animals - I just love their complicated structure and their often fantastical body shapes. We found quite a few on Chesterfield. On land were hermit crabs – this ordinary looking tiny shell on the beach....

 

 

would after a few minutes get up and walk away......

 

 

Note the eyes – these crabs have excellent vision. Their eyes are compound, like insects, giving a large number of small images from which the crabs brain can construct a picture. They are particularly good for spotting movement.

There were bigger ones too, like this one living (almost) in an old whelk shell. You can clearly see his two pairs of antennae ( a diagnostic feature of crustacea, distinguishing them from all other arthropods):

 

 

On the rocks in the intertidal zone were the usual sally lightfoot crabs, scurrying away furiously when disturbed. Here is one, poised for action; note the flattened body section which confers two benefits – it reduces drag when a wave breaks over him, and it enables him to squeeze into narrow crevices under rocks to avoid predators:

 

 

And just look at his structure in close-up; absolutely wonderful. It is still a mystery to me how they manage to shed their shells which they must do in order to grow – even the lenses of their eyes!:

 

 

Below the tideline Ali found this beautiful crayfish (not a lobster because they have claws and live in the Atlantic). No more photographs avbailable because it was so large she panicked and swam away: