The lifespan of a crab varies according to species. A blue crab lives one to eight years, while a hermit crab lives 30 to 70 years. The Dungeness crab lives up to 10 years, and the horseshoe crab lives up to 20 years or more.
Red king crabs live up to 30 or more years. Crab life expectancies also vary according to habitat. Crabs kept as pets can live longer than crabs in the wild when they are properly cared for. Crabs are widely eaten by humans, making up 20 percent of all marine crustaceans that are farmed or caught around the world.