Gizzard
A gizzard is a specialized stomach with a thick, muscular wall used for grinding up food. It is found in birds, reptiles, earthworms, some fish, insects, mollusks, and other creatures. In certain insects and mollusks, the gizzard features chitinous plates or teeth.
The gizzard is also known as a ventriculus, a gastric mill, or a gigerium.
Name
The word "gizzard" comes from the Middle English giser, which derives from a similar word in Old French, and earlier from the Vulgar Latin "*gicerium", which follows from the Latin word "gigeria", meaning cooked entrails of poultry. The Latin word "gigeria" probably is derived from the Persian word for liver, which is "jigar".
Structure
Birds swallow food and store it in their crop if necessary. Then the food passes into their glandular stomach, aka the proventriculus aka the true stomach. This is the secretory part of the stomach. Then the food passes into the ventriculus aka the muscular stomach aka the gizzard. The gizzard can grind the food with stones that have been swallowed and pass it back to the true stomach and vice versa. Bird gizzards are lined with a tough layer made of the protein keratin, to protect the muscles in the gizzard.
Gizzard stones
Some animals that lack teeth will swallow stones or grit to aid in digestion. All birds have gizzards, but not all will swallow stones or grit. However, the birds that do, employ the following method of 'mastication':
- "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 are usually smooth and round from the polishing action in the animal's stomach. When too smooth to do their required work, they may be passed or regurgitated.
Animals with gizzards
Emus, turkeys and chickens, like all birds, have gizzards. Mullet, (mugillidae) found in estuarine waters worldwide, the gizzard shad, or mud shad, found in freshwater lakes and streams from New York to to Mexico, have gizzards. the Gillaroo (Salmo stomachius), has a gizzard. It is a species of trout found in Lough Melvin in County Fermanagh, Ireland. it is a distinct species, characterised by a rich coloration. Its gizzard is used to aid the digestion of water snails, its main item of diet.
Crocodiles also have gizzards.
Dinosaurs with Gizzards
Dinosaurs who are suspected to have gizzards because of gizzard stones found near their fossils include:
- Claosaurus
- Psittacosaurus
- Massospondylus
- Sellosaurus
- Omeisaurus
- Apatosaurus
- Barosaurus
- Dicraeosaurus
- Seismosaurus
Eating gizzards
The gizzards of poultry are a popular food the world over. Grilled chicken gizzards are sold as street food in South Korea, China, Taiwan, Japan, Philippines, Haiti and the rest of Southeast Asia. Stewed gizzards are eaten as a snack in Portugal, while pickled turkey gizzards are a traditional food in some parts of the Midwestern United States. In the Southern United States, the gizzard is typically served fried, sometimes eaten with hot or honey mustard sauce.
Giblets consist of the heart, liver and gizzard of a bird, and are often eaten.
Sources
- Solomon, E.P., Berg L.P., and Martin D.W., 2002. Biology Sixth Edition. Thomson Learning Inc., Australia, Canada, Mexico, Singapore, Spain, United Kingdom, United States pp. 664
- Dyce, Sack, Wensing, 2002. Textbook of Veterinary Anatomy Third Edition, Saunders. ISBN 0-7216-8966-3