Spiders and Seaworld

be stuck in a room where the floor is covered in a layer of spiders

• Spiders are small and individually defeatable — you can stomp them — whereas there is no realistic way to physically fight off a great white shark.
• A confined, hungry shark becomes increasingly dangerous over time; spiders in a room don't collectively hunt or coordinate an attack.
• Most spiders are harmless, and even in large numbers pose far less lethal risk than a single great white at close range in the water.