Crop (anatomy)
A crop (sometimes called a croup or craw) is a thin-walled expanded portion of the alimentary canal used for storing food before digestion. It is found in many animals. It occurs in birds, some dinosaurs, and invertebrate animals such as gastropods (snails and slugs), earthworms,[1] leeches,[2] and insects.[3]
Birds
In a bird's digestive system, the crop is an expanded, muscular pouch near the gullet or throat. It is a part of the digestive tract, essentially an enlarged part of the oesophagus. As with most other organisms that have a crop, the crop is used to temporarily store food. Not all birds have a crop. In adult doves and pigeons, the crop can produce crop milk to feed newly hatched birds.[4]
Scavenging birds, such as vultures, gorge themselves when prey is abundant, causing their crop to bulge. They then sit, sleepy or half torpid, to digest their food.
Most raptors, including hawks, eagles and vultures (as stated above), have a crop; however, owls do not.
Bees
Cropping is used by bees to temporarily store nectar of flowers. When bees "suck" nectar, it is stored in their crops.[5] Pollen is stuffed into their knee bags.
Difference to gizzard
In a gizzard, the food is ground down before digestion, usually by stones. Gizzards have a tougher lining, and muscles. The gizzard is lower down the digestive tract, and more like a part of the stomach.
The crop is just a storage device. Often, it pays a bird to feed while the going is good, and do the digestion later. In many birds and in bees, the food is eventually brought back to the nest and given to family members.
In other species, food brought back to the nest is pre-digested. That would mean it is regurgitated (brought up) from the stomach.
Crop (anatomy) Media
Two white-bellied parrots with bulging crops after feeding.
As a graylag goose eats grass, the full crop is clearly visible.
The crop (serial 4) of a pigeon (Columba livia) is prominently seen at the beginning of the alimentary canal.
Related pages
- Oesophagus
- Gizzard
- Gular pouch, in bird anatomy, a flap generally used to store fish and other prey while hunting
- The word "gular" refers to the bird or reptile's crop.
References
- ↑ "Worm World: About Earthworms". Archived from the original on 2008-12-04. Retrieved 2008-12-16.
- ↑ Sawyer, Roy T. "Leech Biology and Behaviour, Volume II" (PDF). Archived from the original (PDF) on 2005-06-01. Retrieved 2008-12-16.
{{cite journal}}: Cite journal requires|journal=(help) - ↑ "Insect Identification: Digestive System". Retrieved 2011-01-18.
- ↑ Gordon John Larkman Ramel (2008-09-29). "The Alimentary Canal in Birds". Retrieved 2008-12-16.
- ↑ "Honeybee Biology". 1994. Archived from the original on 2020-06-01. Retrieved 2008-12-16.