This is a description of the Japanese Spider Crab, a species of marine crab found in the waters of Japan. It is the largest arthropod in the world, with a leg span of up to 4.5 meters (15 feet). Its body is covered in a hard, spiny
From Wikipedia
The Japanese giant spider crab is a species of marine crab and is the largest crab found in the waters around Japan. At around 3.75 metres (12.3 ft), it has the largest leg-span of any arthropod. The Japanese name for this species is taka-ashi-gani,, literally translating to "tall-legged crab". It goes through three main larval stages along with a prezoeal stage to grow to its full size.