The pneumostome or breathing pore is a respiratory opening of the external body anatomy of an air-breathing land slug or land snail. It is a part of the respiratory system of gastropods. It is an opening in the right side of the mantle of a

stylommatophora Stylommatophora is an orderPhilippe Bouchet, Jean-Pierre Rocroi, Bernhard Hausdorf, Andrzej Kaim, Yasunori Kano, Alexander Nützel, Pavel Parkhaev, Michael Schrödl and Ellen E. Strong. 2017. Revised Classification, Nomenclator and Typification ...

n snail or slug. Air enters through the pneumostome into the animal's single lung, the air-filled mantle cavity. Inside the mantle cavity the animal has a highly

vascular Blood vessels are the structures of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away from ...

ized area of tissue that functions as a lung. The pneumostome is often much easier to see in slugs than in snails, because of the absence of a shell which can often block the view of this area. In a land slug, when the pneumostome is wide open, it is usually very clearly visible on the right side of the animal. However, the position of the pneumostome is often not at all easy to discern when this orifice is completely closed. The pneumostome opens and closes in a cyclical manner. The frequency of pneumostome closing and opening is typically less than 0.5 closures per minute in fully hydrated slugs and snails. The rate of closures per minute increases the more dehydrated the slug is.Pneumostome's response to dehydration
The pneumostome rhythm in slugs: a response to dehydration controlled by hemolymph osmolality and peptide hormones. Dickinson PS, Prior DJ, Avery C. Source Department of Biology, Bowdoin College, Brunswick, ME 04011.

Position of pneumostome as a diagnostic feature

The images in the gallery below show the position of the pneumostome in three different families of slugs: Image:Black slug.jpg, Arionidae, (''

Arion ater Arion (; grc-gre, Ἀρίων; fl. c. 700 BC) was a kitharode in ancient Greece, a Dionysiac poet credited with inventing the dithyramb. The islanders of Lesbos claimed him as their native son, but Arion found a patron in Periander, tyrant ...

''), the pneumostome is just anterior to the midpoint of the mantle Image:Bielzia coerulans-1.jpg,

Limacidae Limacidae, also known by their common name the keelback slugs, are a taxonomic family of medium-sized to very large, air-breathing land slugs, terrestrial pulmonate gastropod molluscs in the superfamily Limacoidea. Distribution The distributi ...

, ('' Bielzia coerulans''), the pneumostome is just posterior to the midpoint of the mantle Image:Tandonia budapestensis 2.jpg, Milacidae, ('' Tandonia budapestensis''), the pneumostome is just posterior to the midpoint of the mantle

References

External links

Short clip of ''Ariolimax columbianus'' displaying its pneumostome
YouTube, Feb 17, 2008 Gastropod anatomy Invertebrate respiratory system Articles containing video clips {{respiratory-stub