The ocean’s depths hold a profound allure, harboring creatures that defy imagination with their immense size and unique adaptations. These vast, unexplored regions continue to reveal astonishing forms of life. Among the many giants of the deep, one question frequently emerges: what truly is the world’s largest crab?
The World’s Largest Crab
The world’s largest crab is the Japanese Spider Crab (Macrocheira kaempferi). It is known for its exceptionally long, slender legs and impressive leg span. Some specimens have been recorded with a leg span extending up to 12 feet (3.7 meters) from claw to claw, making it the arthropod with the greatest linear dimension.
While its legs are long, the crab’s central body, or carapace, is comparatively smaller. The carapace can measure up to 15 inches (38 centimeters) wide and 16 inches (41 centimeters) long. The Japanese Spider Crab can weigh up to 44 pounds (20 kg). Males typically exhibit longer chelipeds, the claw-bearing legs, compared to females.
Physical Characteristics and Habitat
The Japanese Spider Crab possesses a distinct appearance, characterized by its long, jointed legs and a relatively compact, pear-shaped body. Its shell is often orange with white patches, and it features short, spiny tubercles covering the carapace. Two thin spines protrude between its eyes.
This species primarily inhabits the cold, deep waters of the Pacific Ocean, particularly off the southern coasts of Japan, from Tokyo Bay to Kagoshima Prefecture. They are found on the sandy and rocky continental shelf and slope, typically residing at depths ranging from 160 to 1,970 feet (50 to 600 meters). Adults are commonly found around 656 feet (200 meters), where water temperatures are consistently cool, often around 50°F (10°C). These adaptations suit them for the deep-sea environment.
Unique Biology and Longevity
The Japanese Spider Crab is primarily a scavenger, with its diet consisting mainly of dead and decaying animals, including fish, invertebrates, and shellfish found on the seafloor. They are also known to consume algae and can sometimes pry open mollusks. Their slow-moving nature means they do not actively hunt, but rather forage for available food sources.
This deep-sea dweller can live for up to 100 years or more in its natural habitat, making it one of the longest-living arthropods. Reproduction occurs when females carry fertilized eggs on their abdominal appendages, with up to 1.5 million eggs laid per season. The molting process, where the crab sheds its exoskeleton to grow, can take several hours, during which the crab is vulnerable until its new shell hardens.