Crop (anatomy)
A food-storage pouch in the digestive tract of many animals.
The crop, also called the craw or ingluvies, is a thin-walled, expanded section of the digestive tract that stores food before it is digested. (Note: The terms 'croup' and 'sublingual pouch' are not synonyms for the crop; 'croup' refers to the rump area, and the sublingual pouch is a separate structure in the throat or mouth.) This structure appears in vertebrate animals like birds, as well as in invertebrates such as gastropods (snails and slugs), earthworms, leeches, and insects.
Among insects, bees use their crop to temporarily store flower nectar after sucking it up. Other Hymenoptera also store liquid food in their crop. In eusocial insects like ants, the crop has become specially distensible, allowing for important communication between colony members through trophallaxis. The crop is located in the insect foregut.
In birds, the crop is a muscular, expanded pouch near the throat or gullet, forming an enlarged part of the esophagus. It temporarily holds food, though not all bird species have one. In adult doves and pigeons, the crop produces crop milk to feed newly hatched chicks. Scavenging birds like vultures will overeat when prey is plentiful, causing their crop to bulge, and then they sit drowsy or half-torpid while digesting. Most raptors—including hawks, eagles, and vultures—have a crop, but owls do not. All true quail (both Old World and New World) have a crop, but buttonquail lack one. Chickens, turkeys, ducks, geese, and parrots also possess a crop. Pigeons have crops, and one domestic breed is bred to exaggerate the typical crop-inflating behavior so that the crop swells like a balloon. Some extinct birds, such as Enantiornithes, did not have crops.
In literature, the Sherlock Holmes story "The Adventure of the Blue Carbuncle" (1892) features a valuable gem hidden inside a bird's crop. The obsolete term "craw" for crop survives in the saying "it sticks in my craw," meaning something is unacceptable or annoying—metaphorically impossible to swallow.
- Type
- anatomical structure
- Also known as
- craw, ingluvies
- Found in
- birds, gastropods, earthworms, leeches, insects
- Function
- storage of food before digestion
- Location in birds
- expanded, muscular pouch near the gullet or throat, part of the esophagus
- Location in insects
- foregut
Lore & Background
In birds, the crop is an expanded, muscular pouch near the gullet or throat, essentially an enlarged part of the esophagus. It is used to temporarily store food. Not all bird species have one; for example, owls lack a crop, while most raptors including hawks, eagles, and vultures possess one. Scavenging birds such as vultures will gorge themselves when prey is abundant, causing their crop to bulge, and then sit sleepy or half torpid to digest. In adult doves and pigeons, the crop can produce crop milk to feed newly hatched birds. Some extinct birds like Enantiornithes did not have crops.
In insects, cropping is used by bees to temporarily store nectar of flowers. When bees 'suck' nectar, it is stored in their crops. Other Hymenoptera also use crops to store liquid food. In eusocial insects such as ants, the crop has specialized to be distensible, enabling important communication between colonial insects through trophallaxis. The crop can be found in the foregut of insects.
Literary references include the Sherlock Holmes story 'The Adventure of the Blue Carbuncle' (1892), where a valuable gem is hidden inside a bird's crop. The obsolete term 'craw' persists in the saying 'it sticks in my craw,' meaning a situation is unacceptable or annoying.
Reader's Guide
The crop is a significant anatomical adaptation across diverse animal groups, serving primarily as a temporary food storage organ that allows animals to process food in stages. In birds, its presence or absence varies by species, influencing feeding behavior and digestion; for instance, scavengers like vultures can gorge and then digest at leisure, while pigeons use the crop to produce nutrient-rich crop milk for their young. In insects, particularly eusocial species like ants and bees, the crop has evolved beyond simple storage to facilitate trophallaxis—a key mechanism for colony communication and food sharing. The crop's role in both individual survival and social organization highlights its evolutionary importance. Its mention in literature and common idioms also reflects its cultural resonance, as seen in the Sherlock Holmes story and the phrase 'sticks in my craw.' Understanding the crop's structure and function provides insight into the digestive strategies of vertebrates and invertebrates alike.
Did You Know?
- The crop is also called the croup, the craw, the ingluvies, and the sublingual pouch.
- In eusocial insects such as ants, the crop is specialized to be distensible, enabling trophallaxis for communication.
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