Question
The differentiation of alimentary canal into mouth, buccal cavity, pharynx, oesophagus, crop, stomach, intestine, rectum and anus describes which one of the following?
This question was previously asked in
CUET PG 2026 Agri-Business Management Question Paper (25-Mar-2026) (Shift 2)
The correct answer is Hirudinaria
Alimentary Canal Differentiation in Hirudinaria
The differentiation of the digestive tract into specific regions is a key characteristic used in classifying animals. The sequence described – mouth, buccal cavity, pharynx, oesophagus, crop, stomach, intestine, rectum, and anus – points towards a specific type of organism.
Analysis of Digestive System Structures
Let's analyze the digestive system of the given options:
- Hirudinaria (Leech): Leeches possess a specialized digestive system adapted for feeding, often on blood. Their system typically includes a mouth, pharynx, esophagus, a prominent crop for storing ingested food (like blood), a distinct stomach for digestion, followed by the intestine, rectum, and anus. The presence of a buccal cavity is also noted. This closely matches the description.
- Pheretima (Earthworm): Earthworms also show differentiation, including a crop and often a gizzard (sometimes referred to broadly as part of the stomach complex) before the intestine. However, the specific details and emphasis in the question might favor the leech.
- Nereis (Marine Annelid): Polychaetes like Nereis generally have a simpler digestive tract without a distinct, enlarged crop typical of leeches or earthworms.
- Ascaris (Roundworm): Nematodes like Ascaris have a much simpler digestive tube consisting of a pharynx, esophagus, intestine, and rectum, lacking specialized structures like a crop or a distinctly differentiated stomach after the esophagus.
Conclusion on Differentiation
The described differentiation, particularly the inclusion of a distinct crop and stomach following the esophagus, is characteristic of the annelid group, specifically leeches like Hirudinaria. This specialized structure supports their feeding habits.
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