Giant crabs capture human imagination with their immense sizes. Identifying the largest crab involves examining specific species and their measurement methods.
The Japanese Spider Crab
The Japanese spider crab, Macrocheira kaempferi, is widely recognized as the crab species with the largest leg span in the world. Their legs can extend up to 12 feet (3.7 meters) from claw to claw. Their bodies, or carapaces, can measure up to 16 inches (41 cm) across, and they can weigh as much as 44 pounds (20 kg).
These crabs inhabit the deep waters of the Pacific Ocean, primarily off the coast of Japan, at depths ranging from 160 to 2,000 feet (49-610 meters). Their appearance is distinctive, featuring an orange body with white spots on their long, slender legs and a triangular-shaped carapace covered with small projections. Despite their formidable size and spider-like appearance, Japanese spider crabs are scavengers, feeding on dead animals and shellfish found on the ocean floor.
Documented Record Catches
While the Japanese spider crab is the largest species by leg span, specific individuals have been documented as holding records for their extraordinary size. One notable example is a Japanese spider crab nicknamed “Big Daddy.” This individual was recorded as the widest crustacean ever held in captivity, measuring an astounding 10 feet, 2.5 inches (3.11 meters) across its span. It also held the record for the longest leg on a crab, measuring 4 feet, 8.5 inches (1.43 meters). This particular crab was transported from Japan to the Sea Life Blackpool aquarium in the United Kingdom in 2013, where it lived until its peaceful passing in 2016 at approximately 80 years of age.
How Giant Crabs Are Measured
Measuring giant crabs involves specific techniques to ensure consistency in record-keeping. The two primary measurements are leg span and carapace width or length. Leg span, particularly for species like the Japanese spider crab, refers to the distance from the tip of one claw to the tip of the opposing claw when the legs are fully extended. This measurement highlights the impressive reach of their limbs.
Carapace width is typically measured across the widest point of the main body shell, often from point to point or between specific anatomical markers. Carapace length is measured along the mid-dorsal line from the anterior to the posterior margin of the shell. Accurately measuring live or recently caught giant crabs can be challenging due to their size, the flexibility of their limbs, and their deep-sea habitat. Establishing consistent measurement standards is important for comparing sizes and verifying record-breaking individuals.