As a Noun:
1. A sea creature with a flat round body covered by a shell, and five pairs of legs with large claws on the front pair. They usually move sideways. English = crab.
2. The claws on the front of a crab or lobster. English = pincers.
3. A sea creature that has a hard shell, two large claws, and eight legs. English = lobster.
4. A small shellfish with five pairs of legs which lives in rivers and ponds. It has strong pincers on its front legs which it uses for catching food. English = crayfish.
As a Verb or Adjective:
1. Of a crab, lobster or crayfish, to open and close its pincers.