​Giant spider crabs at Underwater World, Sentosa, Singapore

Thought to be the largest arthropods on Earth, giant spider crabs spend their time foraging on the ocean floor up to a thousand feet (300 meters) deep. These rare, leggy behemoths, native to the waters off Japan, can measure up to 12 feet (3.7 meters) from claw tip to claw tip. This five-foot (1.5-meter) specimen was photographed in Japan's Sagami Bay.