What is the heaviest species of crustacean in the world?

The American lobster is the heaviest living crustacean species in the world. Its scientific name is Homarus americanus, and exceptionally large individuals can reach about 64 centimeters in body length and weigh more than 20 kilograms.

American lobsters live along the western Atlantic coast, chiefly from Labrador to New Jersey. They are also called Atlantic, Canadian, northern, or Maine lobsters. Their familiar claws are powerful tools for crushing shells and tearing food, while their antennae and sensory hairs detect chemical traces and water movement.

The record is easy to confuse with other impressive crustaceans. The Japanese spider crab has a greater leg span, and the coconut crab is the largest land-dwelling arthropod, but neither is heavier than the largest American lobster. Guinness World Records lists a 44.4-pound American lobster caught off Nova Scotia as the heaviest crustacean ever recorded. The animal’s size is also linked to its ability to keep molting throughout life, although growth becomes slower and riskier with age.