TIL, that the largest arthropod in the world is a spider crab with a width of over 12 feet and weighing in at nearly 45 pounds! Known as the Japanese Spider Crab.

For the rest of the world: 12 feet = 3.66 metres 45 pounds = 20.45 kilograms

Or to round the numbers a bit: They have a leg span of up to 3.7 metres, though their body is usually just 37 centimetres (15 inches) wide. They weigh about 16 to 20 kilograms.