Earthworms have a crop near the beginning of their digestive tract.
A crop is part of the digestive tract of many birds and also some other creatures, such as insects and earthworms. Essentially, it acts as a storage container to hold food until the body can process it. In some cases, people can even see the area in a bird’s eye view; Baby birds tend to have full, bulging plantings that can look like strange cancerous growths on the bird’s neck to the uninitiated.
Little birds usually have pronounced crops.
Birds are probably the most famous for having crops, although the area works the same way with other animals. Essentially, since birds don’t have teeth, they rely on a predigestive system to process the food they eat so it can be broken down in the stomach. When an old bird swallows food, it stops at this part of the digestive tract, which softens the food before passing it to the gizzard, a muscular organ that grinds the food up, often with the help of small stones. Then the food can be digested.
In addition to being used to prepare food for digestion, the crop also serves as a storage compartment, allowing birds to gorge themselves. In scavengers this can be extremely helpful as it allows the bird to fill up on a good meal and process the food slowly. Other birds take the opportunity to eat a large amount of food and then dart to a safe place to digest it in peace, away from predators. The culture is also used to store food for young birds, with the contents being regurgitated by the parents when requested.
The crop is quite muscular and designed to expand, sometimes even many times its size. When not in use, it can often feel like a normal part of the esophagus, until it begins to fill with food, at which point it swells up like a little balloon. As the food is pushed into the gizzard, the area shrinks again.
When the harvest is full, it can often be felt. To feel one in a bird, one can gently place a finger on the top of the bird’s chest, just around the area where the neck meets the chest. If you rub the area, you will feel something that looks like a sandbag, being very hard and obviously gritty. This is the crop and if the person checks it in a few hours it will probably have shrunk unless the bird eats again.