canal
From ZooTerms (Dictionary of Invertebrate Zoology)
tube, or duct.
canal (noun; Latin canalis, channel): 1. A groove,
2. (Arthropoda: Insecta) The groove or sulcus on the mandible or mouth structures of insect larvae.
3. (Cnidaria) Part of the gastrovascular system; in medusae may be radial or circular with interconnections.
4. (Mollusca: Gastropoda) A narrow, semitubular extension of the aperture.