To make these crabs you need four small circles of the same colour, folded in half. Then you need one large circle of the same colour folded in half.
You stick the large folded circle down on your backing page, colour in a mouth and two eyes and six legs at the bottom. Then you draw in two claw legs. Where these claw legs finish you put a pair of two small circles folded to look like crab pinchers and you do the same to the other crab leg.
You can make many crabs for your picture this way.
(photos to follow)