Captain Claw is a villainous crab from Mobius who used to patrol the Mobian Channel in search of wayward travellers. The "captain" (who wears some sort of sailor's cap) seems to enjoy torturing the people he discovers, especially since he gets to give his Octonaught Badnik a bit of exercise. Claw is particularly happy when Knuckles the Echidna stumbles across his territory and wishes to claim the reward from Doctor Robotnik for capturing him (although it's not quite as big a reward than if Sonic the Hedgehog was captured). Claw not-so-secretly hoped Knuckles would resist arrest, giving him a chance to put the Octonaught through its paces. He also enjoyed it when Knuckles electrocuted himself on the ship's underbelly and continuously gave the echidna a chance to give up.
Claw continued to wear Knuckles down, shooting the rocky stacks that the echidna attempted to rest on. Unfortunately, one such pillar fell on top of the Octonaught, crushing it and leaving Claw stranded in the channel. Now unarmed, Claw was forced into rowing him and Knuckles to shore. Claw continued to complain, saying that a "prisoner of war" shouldn't be treated this way.
Despite trying to murder Knuckles (or at least capture him), the echidna was forced to release Claw when they got to land, the current legal system not being very good under Robotnik's rule.