The gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ found in the digestive tract of some animals, including archosaurs (pterosaurs, crocodiles, alligators, and dinosaurs, including birds), earthworms, some gastropods, some fish, and some crustaceans. This specialized stomach constructed of thick muscular walls is used for grinding up food, often aided by particles of stone or grit. In certain insects and molluscs, the gizzard features chitinous plates or teeth.
Birds swallow food and store it in their crop if necessary. Then the food passes into their glandular stomach, also called the proventriculus, which is also sometimes referred to as the true stomach. This is the secretory part of the stomach. Then the food passes into the gizzard (also known as the muscular stomach or ventriculus). The gizzard can grind the food with previously swallowed stones and pass it back to the true stomach, and vice versa. In layman's terms, the gizzard 'chews' the food for the bird as it does not have teeth to chew food the way humans do. Bird gizzards are lined with a tough layer made of the carbohydrate-protein complex koilin, to protect the muscles in the gizzard.
By comparison, while in birds the stomach occurs in the digestive tract prior to the gizzard, in grasshoppers the gizzard occurs prior to the stomach, while in earthworms there is only a gizzard, and no stomach.
Some animals that lack teeth will swallow stones or grit to aid in fragmenting hard foods. All birds have gizzards, but not all will swallow stones or grit. Those that do employ the following method of chewing:
- "A bird swallows small bits of gravel that act as 'teeth' in the gizzard, breaking down hard food such as seeds and thus helping digestion." (Solomon et al., 2002).
These stones are called gizzard stones or gastroliths and usually become round and smooth from the polishing action in the animal's stomach. When too smooth to do their required work, they may be excreted or regurgitated.
Animals with gizzards
The mullet (Mugilidae) found in estuarine waters worldwide, and the gizzard or mud shad, found in freshwater lakes and streams from New York to Mexico, have gizzards. The gillaroo (Salmo stomachius), a richly colored species of trout found in Lough Melvin, a lake in the north of Ireland, has a gizzard which is used to aid the digestion of water snails, the main component of its diet.
Earthworms also have gizzards.
Some crustaceans have a gizzard although this is usually referred to as a gastric mill.
Dinosaurs that are believed to have had gizzards based on the discovery of gizzard stones recovered near fossils include:
In Mexico they are eaten with rice or with chicken soup. They are also served grilled and prepared scrambled with eggs, onions, garlic, and salsa; and served with beans and tortillas for breakfast and other meals.
Stewed gizzards are eaten as a snack in Portugal.
In Ghana, it is eaten boiled, fried or grilled. Grilled, skewered gizzards, with spices and optional green peppers and onions, are popular.
Pickled turkey gizzards are a traditional food in some parts of the Midwestern United States. In Chicago, gizzard is battered, deep fried and served with french fries and sauce. The Chamber of Commerce in Potterville, Michigan has held a Gizzard Fest each June since 2000; a gizzard-eating contest is among the weekend's events. In the Southern United States, the gizzard is typically served fried, sometimes eaten with hot sauce or honey mustard, or added to crawfish boil along with crawfish sauce, and it is also used in traditional New Orleans gumbo.
Gizzard and mashed potato is a popular food in many European countries.
The word Sangdana is commonly used to refer to chicken gizzards in Northern India and Pakistan. The word is derived from Persian (Sang = stone and dana = grain). Another name for it is Pathri. It may be served cooked in a curry while barbecued skewered gizzards are also popular.
In Nepal, gizzard is called jaatey or pangra. It is eaten most often with drinks.
In Yiddish, gizzards are referred to as pipik'lach, literally meaning navels. The gizzards of kosher species of birds have a green or yellowish membrane lining the inside, which must be peeled off before cooking, as it lends a very bitter taste to the food. In traditional Eastern European Jewish cuisine, the gizzards, necks, and feet of chickens were often cooked together, although not the liver, which per Kosher law must be broiled. Kosher butchers often sell roasting chickens with the gizzard, neck, and feet butchered and left in the cavity to be used for making chicken soup.
Giblets consist of the heart, liver and gizzard of a bird, and are often eaten themselves or used as the basis for a soup or stock.
In Taiwan, gizzards are often slow-cooked and served hot or cold in slices, with green onions and soy sauce.
In Mainland China, duck gizzard is a common snack, eaten alongside other duck parts such as feet, neck, heart, tongue, or head. Areas famous for their gizzard are Sichuan and Hubei provinces. Wuhan city in Hubei is famous for its brand of spicy gizzard, called Jiujiuya (Simplified Chinese:久久鸭). In Northern China, one can find barbecued duck gizzard.
The term "gizzard" can also, by extension, refer to the general guts, innards or entrails of animals.
- "Gizzard". Merriam-Webster Online Dictionary. Retrieved 2009-02-05.
- K. Sakai (2004). "The diphyletic nature of the Infraorder Thalassinidea (Decapoda, Pleocyemata) as derived from the morphology of the gastric mill". Crustaceana. 77 (9): 1117–1129. doi:10.1163/1568540042900268. JSTOR 20107419.
- Creisler, Benjamin S (2007). Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs. Bloomington: Indiana University Press. p. 199. ISBN 978-0253348173.
- Codorniú et al. 2009
- Wilton, Mark P. (2013). Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press. ISBN 0691150613.
- "Gizzard Fest". Potterville Chamber of Commerce. Retrieved 2009-02-05.
- Victor Mair (2015), Chinese words and characters for "gizzard", Language Log, 7 January 2015.