Crabs can range in size from a few millimeters wide to the Japanese Spider Crab, which has a leg span of up to 13 feet. Most crabs display sexual dimorphism, which means you can usually tell a male crab from a female because males tend to have larger claws, or one claw that is enlarged for attracting a mate.
Crabs are found in all of the world’s oceans, as well as in freshwater and on land.
Crabs have a variety of prey, including algae, worms, other crustaceans, snails, mussels, etc.
Crabs have many natural predators, including birds, fish, seals, some terrestrial mammals such as raccoons, etc. Crabs are also a food source for humans, as they make up 20% of all marine crustaceans caught, farmed or consumed.