All crocodilians share similar morphology. They are longer than they are tall, and much of a crocodilian's body length consists of a long tail the crocodilian uses to aid in swimming and as a weapon when defending itself. On land, crocodilians use their short, laterally positioned legs to propel them forward, and can move surprisingly quickly in short bursts. Crocodilians typically have thick, knobby scales along their backs. Their smoother and softer underbellies however, leave them vulnerable to attacks from below. A crocodilian's most notable physical feature is the large mouth that houses a menacing array of sharp teeth. Its powerful jaws can snap closed quickly and remain clamped on captured prey.