Exoskeleton - Growth in An Exoskeleton

Growth in An Exoskeleton

Since exoskeletons are rigid, they present some limits to growth. Organisms with open shells can grow by adding new material to the aperture of their shell, as is the case in snails, bivalves and other molluscans. A true exoskeleton, like that found in in arthropods must be shed (moulted) when they are outgrown. A new exoskeleton is produced beneath the old one. As the old one is shed, the new skeleton is soft and pliable. The animal will pump itself up to expand the new shell to maximal size, then let it harden. When the shell has set, the empty space inside the new skeleton can be filled up as the animal eats. Failure to shed the exoskeleton once outgrown can result in the animal being suffocated within its own shell, and will stop subadults from reaching maturity, thus preventing them from reproducing. This is the mechanism behind some insect pesticides, like Azadirachtin.