Amphibious. The crab can breathe air and water.
Multiattack. The mudcrab can Pinch twice on each of its turns. Pinch. Melee Weapon Attack: +3 to hit, reach 5 ft, one target. Hit: 4 (1d4 + 1) bludgeoning damage, and the target is grappled (escape DC 11). The crab has two claws, each of which can grapple only one target.