What is the world's largest type of crab by leg span?

The world's largest type of crab by leg span is the Japanese spider crab (Macrocheira kaempferi). Adult Japanese spider crabs can have a leg span of up to 3.8 meters (12 feet), which is longer than most adult human's heights.

These crabs are found in the waters around Japan and live at depths of up to 300 meters (984 feet). They have a hard, spiky exoskeleton that helps protect them from predators, and they feed on a variety of sea creatures, including fish, mollusks, and other crabs.

Despite their large size, Japanese spider crabs are not typically aggressive towards humans and are not considered dangerous. They are a popular attraction in many aquariums around the world, where visitors can observe them up close.

The Japanese spider crab is the world's largest type of crab by leg span. It has the greatest leg span of any known arthropod, reaching up to 3.7 m (12.1 ft) from claw to claw. The body may grow to 40 cm (16 in) in carapace width and the whole crab can weigh up to 19 kg (42 lb)—second in mass only to the American lobster among all living arthropod species. The males have the longer chelipeds; females have much shorter chelipeds, which are shorter than the following pair of legs. Apart from its outstanding size, the Japanese spider crab differs from other crabs in a number of ways. The first pleopods of males are unusually twisted, and the larvae appear primitive.

The Japanese spider crab is a species of marine crab that lives in the waters around Japan. It is found at depths of 200 to 800 meters (660 to 2,625 feet). It is a bottom-dweller and is usually found on muddy or sandy bottoms. The Japanese spider crab is a scavenger and feeds on a variety of things, including dead fish, shellfish, and algae.

The Japanese spider crab is a slow-moving crab and is not considered to be a threat to humans. However, it is a popular food source in Japan and is often caught for commercial purposes.