Sculpture (mollusc)
Appearance
![](http://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Epitonium_scalare.jpg/220px-Epitonium_scalare.jpg)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/2/21/Bulinus_forskalii_shell.png/220px-Bulinus_forskalii_shell.png)
Sculpture is a feature of many of the
ammonites, and to the outer surface of some calcareous opercula of marine gastropods such as some species in the family Trochidae.[1]
Sculpture can be
microscopic detailing. The term "sculpture" refers only to the calcareous outer layer of shell, and does not include the proteinaceous periostracum
, which is in some cases textured even when the underlying shell surface is smooth.
In many
taxa
, there is no sculpture on the shell surface at all, apart from the presence of fine growth lines.
The sculpture has a protective function because it increases the diameter of the shell, distributing mechanical stress (such as the force of a predator's jaws) across a larger surface area.[2]
List of terms
- Axial sculpture - Sculpture running parallel to the axis of coiling, an imaginary line through the apex of a shell about which the whorls are coiled.
- Bead - A small hemispherical protuberance resembling a bead, similar to but smaller than a nodule.
- Beaded - resembling rows or strings of beads.
- Growth line - A fine transverse line marking the growth of the shell.
- Lira, lirate - ornamented with fine thread-like lines or grooves.
- Longitudinal sculpture - Sculpture following the direction of the axis of the shell.
- Nodule - A rounded protuberance on the shell sculpture; larger than a bead.
- Nodose, Nodulose, Nodular - Bearing small rounded protuberances or tubercules.
- Ornament - Can refer to surface sculpture standing out in relief on shell surface; or simply to sculpture as a whole.
- Plait - Folds on the columella.
- Pustule - A very fine knob-like protrusion, smaller than a tubercule.
- Reticulate - Sculpture consisting of a criss-crossing network of riblets, threads, or grooves.
- Rib - A strong ridge on the surface of the shell.
- Riblet - Smaller than a rib, but coarser than a thread.
- Spiral sculpture - Sculpture following the spiral growth of the shell.
- Stria (plural striae) - A shallow incised groove.
- Striate - Ornamented with striae.
- Thread - A very fine riblet.
- Transverse sculpture - Sculpture parallel to the edge of the outer lip of the aperture.
- Tubercle - Elevated knob-like projections or protrusions; larger than a pustule.
- Varicose - Bearing one or more varices.
See also
- Sculpturing— arthropod equivalent