Gastropods have a continuous hollow shell. As you can see in the cross-section below the shell does not have any subdivision on the interior of the shell (conch). This is one of the major characteristics which differentiates the Gastropods from the Cephalopods.
This gastropod is a cast. It is from South-Central Missouri from the Gasconade Formation. As you can see the preservation of the cast is good enough to show the growth lines of the gastropod shell.
These are two Pennsylvanian Gastropods that are common in the Pennsylvanian strata of North America. The specimen on the left is Worthenia tabulata, the specimen on the right is Pharkidonotus nodos. Both of the specimens are from the Brush Creek Shale of Western Pennsylvania.
This is Shansiella carbonaria another common species in Pennsylvanian rocks in North America.
Gastropods are one group of invertebrates that have adapted to life on land. The Pulmonate snails have adapted to life on land by:
Here you can see a land snail and its slime trail. As in all gastropods the snail carries its shell on the back. You can see nicely how gastropods got their name of "stomach" "Foot" because they seem to walk around on their stomachs.
- reducing desication by secretion of what you would call slime.
- they maintain a watery sac where the gills are bathed with water, thus they can breath on land, but somewhat in water too.
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