The ocean’s depths hold a diverse array of life, including crabs that reach impressive sizes. Identifying the largest among them reveals remarkable adaptations and unique existences, inviting a closer look into these oversized crustaceans.
The Largest Crab Identified
The title of the world’s largest crab, by leg span, belongs to the Japanese spider crab, Macrocheira kaempferi. This marine arthropod is notable for its exceptionally long limbs, which can stretch up to 3.7 meters (12.1 feet) from claw to claw. Its carapace can reach a width of about 40 centimeters (16 inches) and the crab can weigh up to 19 kilograms (42 pounds). It is the largest living arthropod by leg span, and second only to the American lobster in terms of mass among living arthropod species.
The Japanese spider crab has an orange body with white spots along its legs, and its carapace is covered with spiny tubercles. Male Japanese spider crabs typically have longer chelipeds compared to females. Despite its formidable appearance, it is considered to have a gentle disposition.
Deep-Sea Life of the Giant
The Japanese spider crab inhabits the deep waters off the southern coasts of Japan, primarily from Tokyo Bay to Kagoshima Prefecture, though outlying populations have been found near Taiwan. Adult crabs are typically found at depths ranging from 50 to 600 meters (160 to 1,970 feet), often residing near hydrothermal vents and holes on the seabed. The water temperature in their adult habitat is consistently around 10°C (50°F).
These crabs are omnivorous scavengers, consuming a varied diet that includes dead fish, decaying animals, shellfish, and algae found on the ocean floor. Their long legs enable them to move across the seabed in search of food. Reproduction occurs seasonally, between January and April, when females carry fertilized eggs attached to their abdominal appendages until they hatch into planktonic larvae. Larvae develop through several stages in shallower, warmer waters before descending to greater depths as adults.
Other Impressive Crab Species
While the Japanese spider crab holds the record for leg span, other crab species are also notable for their considerable size. The Tasmanian giant crab, Pseudocarcinus gigas, found in the cold waters off southern Australia, is one of the heaviest crab species. Males of this species can weigh over 17 kilograms (37 pounds) and have a carapace width of up to 46 centimeters (18 inches).
The coconut crab, Birgus latro, is recognized as the largest terrestrial arthropod. Found on islands across the Indian and Pacific Oceans, these land-dwelling crabs can weigh up to 4.1 kilograms (9 pounds) with a leg span exceeding 1 meter (3.3 feet). Known for their powerful pincers, coconut crabs can crack open coconuts, which form a significant part of their diet.