Baby pet crab loves to play peak a boo

We have all seen many trained animals, but have you ever seen a trained crab. Every time when the man says peekabo, the crab in the water tank will lift his claw. Is this crab soluting the commander, or is he treating the man like a baby who loves peekaboo. We think this man is really the pet, and the crab is the commander of beyond the aquarium.