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Ventriculus gastric mill, or gizzard, is a kind of muscular stomach found in birds and earthworms, as well as some types of fish and reptiles. The gizzard is special because it grinds up difficult-to-digest foods, making it particularly useful to animals that lack teeth. A gizzard features a hard, horn-lined surface with which to grind food. Although tough, animal gizzards are edible and are eaten all over the world.
Birds with Gizzards
All birds have gizzards, from hummingbirds to ostriches. The gizzard is especially useful to birds because they don’t have teeth. Instead of chewing their food, many birds swallow stones, allowing the stones to collect in the gizzard where they aid in the process of breaking down foods. Once the stones have done their job, they'll be regurgitated or passed through the rectum. Poultry gizzards, like ones found in turkeys and chickens, are very popular in worldwide cuisine. Pickled turkey gizzards are a Midwestern snack, while grilled chicken gizzards are a popular street food in Haiti.
Earthworms with Gizzards
An earthworm’s digestive system includes a gizzard, as well as a pharynx, esophagus, crop and intestine. Most often, earthworms feed on soil, which is heavy in calcium. The esophagus is responsible for filtering out excess calcium. After food passes through the esophagus, it moves into the crop. Food is stored in the crop, before it moves into the gizzard. Like birds, earthworms keep stones in their gizzard to grind up their food. An earthworm’s food is completely digested when it’s passed into the intestines and absorbed into the body.
Fish with Gizzards
There are a few types of fish with gizzards. The gillaroo, a type of trout found in Irish Lake in County Fermanagh, uses its gizzard to help it digest water snails. Mullets, another fish with a gizzard, can be found in estuary waters around the world. A mullet’s gizzard is a popular snack among fishermen, who prefer it fried separately from the rest of the fish. The mud shad is a type of herring native to New York’s freshwater lakes. Sometimes it’s called the American gizzard shad because it’s one of the few fish with a gizzard.
Reptiles with Gizzards
Despite having sharp teeth, both crocodiles and alligators have gizzards. These reptiles don’t really use their teeth for chewing. Instead, their teeth have the more frightening job of trapping and killing their prey. With no grinding teeth with which to chew meat, the job of breaking down food falls to the reptile’s gizzard. Just like birds and earthworms, they swallow stones to aid in this process. Crocodiles and alligators are the only reptiles, so far known to science, that have gizzards.
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