Gizzard

The gizzard, also referred as the ventriculus, gastric mill, and gigerium.  In Mandarin, it is called 肫 ( pinyin : zhūn ), or 胗 ( pinyin : zhēn )  It is an organ found in the digestive tract of some animals, including birds, reptiles, earthworms, and some fish.  It is a specialized stomach constructed of thick, muscular walls, for grinding up food, often rocks are instrumental in the process.

The word ‘gizzard’ comes from the Middle English ‘giser’, which derives from a similar word in Old French, which evolved from the Latin ‘gigeria’, meaning giblets.

Birds swallow food and store it in their crop.   Then the food passes into their glandular stomach ( proventirculus – true stomach ).  Then into the muscular stomach ( ventriculus – gizzard ).  The gizzard can grind the food with previously-swallowed stones and pass it back to the muscular stomach, and vice versa.  The bird gizzards are lined with a tough layer made of the carbohydrate-protein complex koilin, to protect the muscles in the gizzard and to aid in digestion.

All birds have gizzards.  Some fish ( mullet, gillaroo, trout ), alligators, crocodiles, and most invertebrates too have gizzards.