Crabs exhibit a wide array of sizes and forms, inhabiting diverse environments from the deepest oceans to tropical landmasses. This variation includes tiny species and colossal creatures. One species stands out as the largest among them. This exploration will identify this giant and explain what defines its impressive size.
The Reigning Giant
The Japanese spider crab, scientifically known as Macrocheira kaempferi, holds the title as the largest crab species. Its appearance is distinct, characterized by an orange body with white spots on its legs and a relatively small, spiny carapace. Males are notable for their exceptionally long claw-bearing limbs, which extend significantly beyond their other legs.
These crustaceans reside in the deep waters surrounding Japan, typically found at depths ranging from 160 to 1,970 feet (50 to 600 meters). They often inhabit vents and holes on the ocean floor, functioning as scavengers, feeding on shellfish and the remains of dead animals. Despite their size, Japanese spider crabs are known for their calm demeanor and can live up to 100 years.
Defining “Biggest”
When discussing the “biggest” crab, it is important to clarify the measurement used, as size can be assessed by different metrics. For the Japanese spider crab, its claim to fame lies in its extraordinary leg span. This species boasts the largest leg span of any arthropod, reaching up to 12 feet (3.7 meters) from claw to claw.
The carapace, or body shell, of the Japanese spider crab is comparatively smaller, measuring up to 16 inches (40 cm) in width. In terms of weight, these crabs can reach up to 44 pounds (20 kg). While other crabs may rival or exceed this weight, the Japanese spider crab’s disproportionately long legs are the defining characteristic of its size, making leg span the primary metric for its “biggest” designation.
Other Notable Giants
While the Japanese spider crab is the largest by leg span, other crab species are noteworthy for their substantial size, often measured by weight or carapace width. The coconut crab (Birgus latro) is recognized as the largest terrestrial arthropod by weight. These land-dwelling giants can weigh up to 10 pounds (4.5 kg) and have a leg span of about 3 feet (1 meter), with powerful pincers capable of cracking coconuts. Coconut crabs are found on islands across the Indian and Pacific Oceans.
The Tasmanian giant crab (Pseudocarcinus gigas) is among the heaviest crabs in the world. Living in the deep waters off Southern Australia, males can weigh up to 39 pounds (17.6 kg) and have a carapace width of up to 18 inches (46 cm). Males are notable for possessing one significantly oversized claw.
The giant mud crab (Scylla serrata) also reaches large sizes, with a carapace width of up to 11 inches (28 cm) and a weight of up to 6.6 pounds (3 kg). These crabs are found in sheltered estuaries and mangrove forests across the Indo-Pacific region.