lacuna
From ZooTerms (Dictionary of Invertebrate Zoology)
lacuna (noun; plural lacunae; Latin lacuna, cavity): 1. A space, gap, cavity or channel.
2. (Acanthocephala) Channels making up the lacunar system.
3. (Arthropoda: Insecta) In wing development, canals that contain nerves, tracheae, and hemolymph.
4. (Brachiopoda:Articulata) The large open space surrounding the lophophore.
5. (Bryozoa) Open space between tubular porechambers.
6. (Mollusca: Bivalvia) Irregular, blood-filled spaces between various organs in the mantle and visceral mass.
