Green glands, also called antennal or maxillary glands, help carry out excretory functions in crayfish. These glands act much like kidneys in humans and help crayfish remain healthy by eliminating toxic substances and waste products in their urinary and circulatory systems.
Green glands vary in where they open, but perform the same functions regardless of whether they are situated at the base of the antennae of the maxillae. The glands appear as convoluted ducts with ball-like sacs on their ends that expand and contract when filled with fluids or emptied of liquid substances. Crayfish are born with a pair of green glands and retain both organs throughout their adult lives. Although they always have two glands, only one is functional at a given time. Rarely, adults may have two operational green glands, and it is not uncommon for the glands to exchange productivity cycles throughout the creatures’ lives. Green glands, much like kidneys, help to filter, process and remove impurities and waste products on a daily basis. In crayfish, these organs also regulate iconic balance by controlling the levels of salt and water in the bloodstream and correcting imbalances as they arise. To a lesser extent, green glands regulate glucose and contribute to the end process of digestion by removing waste particles from food.