This brightly-colored crab is known as a red reef crab. It is also sometimes called a dark-finger coral crab or eyed coral crab. This crab species is common in Japan, and it can be found around many of the Japanese islands. It is also found in the waters near Taiwan and Singapore. They live on coral reefs and rocky beaches at a depth of up to 100 feet (30 meters) These crabs grow to a width of about 3.5 inches (9 centimeters).