Cancer productus mate in the summer, and eggs hatch in the winter. Females will hold the eggs for months after breeding. Because this process can take some time, females will often wait until they’ve molted into a bigger shell to produce eggs. This ensures that their shells are big enough to last through the brooding process. Males will often protect females by holding them until their shells harden from their molt, giving their offspring a better chance of survival. Females can carry several hundred thousand eggs at a time and can live for 4-5 years.