Pneumostome

Source: Wikipedia, the free encyclopedia.
Arion vulgaris
opening its pneumostome
Arion rufus
with the pneumostome wide open
Drawing showing the different external anatomical features of a slug
Open and closed pneumostome
Triboniophorus graeffei
is on its dorsal surface.

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

vascularized
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.[2]

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:

  • Arionidae (Arion ater), the pneumostome is just anterior to the midpoint of the mantle
    Arionidae (Arion ater), the pneumostome is just anterior to the midpoint of the mantle
  • Limacidae (Bielzia coerulans), the pneumostome is just posterior to the midpoint of the mantle
    Bielzia coerulans
    ), the pneumostome is just posterior to the midpoint of the mantle
  • Milacidae (Tandonia budapestensis), the pneumostome is just posterior to the midpoint of the mantle
    Milacidae (Tandonia budapestensis), the pneumostome is just posterior to the midpoint of the mantle

References

  1. ^ Fox, Richard (2006). "Invertebrate Anatomy OnLine". Lander University. Retrieved 11 July 2012.
  2. ^ 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.

External links