Shell Anatomy Glossary
A collection of whorls that sits atop the body whorl, often coming to a sharp point.
A 360° spiralling turn of the snail's shell. A line on the outside of the shell between a pair of whorls is called a suture.
The body whorl is the largest whorl on the shell, the last to be grown by the snail. It houses the aperture. The shoulder is the part of the body whorl that extends furthest out from the center (or axis) of the shell and is often (but not always) located just above the aperture.
The section of shell adjacent to the aperture on the inside edge of the body whorl. Can sometimes be called the parietal wall, or form a flat section of shell called a parietal shield. Sometimes the inner lip is also a part of the columella- the central pillar that the shell spirals around.
The section of shell adjacent to the aperture, on the outside edge of the body whorl.
The aperture is the entrance to the shell, from which the snail will extend its body. Living sea snails often can retreat into the shell and cover it with a flat, tough plate called an operculum. The operculum can often be used to identify living shells by species, but is rarely (if ever) found on dead shells.
An tubelike extension of the aperture that some snails use to extend their siphon- an organ used by the snail to direct water over its gills.
Basic Parts of the Gastropod Shell
Identification Key to the Major Groups
- Does the shell lack a spire?
Yes---Go to 2
No----Go to 5
- Does the shell have a low, conical shape?
Yes---Go to 3
No----Go to 4
- Does the shell have a hole on the top?
Yes---Keyhole Limpets
No----True Limpets
- Does the shell have a long, slitlike aperture on the underside (Yes) or an open underside with a shelflike structure (No)?
Yes---Cowrie or Flamingo Tongues
No----Slipper Snails
- Does the shell lack a visible siphonal canal?
Yes---Go to 6
No----Go to 13
- Is the aperture a long slit that extends from the shoulder of the shell down to where the siphonal canal would be?
Yes---Go to 7
No----Go to 8
- Is the shell shaped like a cone (Yes) or a bullet (No)?
Yes---Cone Snails
No----Olive Snails
- Is the shell wide, almost circular?
Yes---Go to 9
No----Go to 11
- Is the aperture very large in relation to the shell- almost half the width?
Yes---Purple Sea Snails
No----Go to 10
- Does the aperture seem to have teeth on the inner lip?
Yes---Nerites
No----Moon Snails
- Is the shell heavily ornamented with ridges or beads?
Yes---Go to 12
No----Periwinkles
- Does the shell have a high, pointed spire composed of many whorls with ridges?
Yes---Wentletraps
No----Turban Snails
- Is the siphonal canal long?
Yes---Go to 14
No----Go to 15
- Does the shell have a very wide aperture and very short spire?
Yes---Whelks
No----Tulip Snails
- Is the spire high, taking up most of the length of the shell?
Yes---Go to 16
No----Go to 17
- Does the shell have a small canal opposite from the siphonal canal?
Yes---Ceriths
No----Augers
- Is the shell's spire and body covered with large spikes, spines, or knobs?
Yes---Go to 18
No----Go to 20
- Is the siphonal canal very wide, almost as wide as the aperture?
Yes---Melongenas
No----Go to 19
- Is there a notch on the outer lip, just by the siphonal canal?
Yes---Conchs
No----Murexes
- Is there a distinctly flattened section of shell adjacent to the inner lip?
Yes---Helmets
No----Go to 21
- Is the aperture surrounded by pronounced teeth?
Yes---Tritons
No----Vases