A coastal shell.
A pointed spire and a large body whorl give this marine snail its stout conical form. Adults typically have five or six whorls, with subtle spiral ridges that can become worn.
Field notes / plate 005 / life on the shore
The common periwinkle.
Littorina littorea
A small sea snail with a substantial home. Explore the shell and the body it protects, then look closer at a grazer’s toothed ribbon.
Exterior
Choose a structure · hidden anatomy is revealed before inspection
Body whorl
The largest whorl houses most of the soft body.
01 / A different view, never a mirrored animal
A right-handed shell.
Face the aperture with the apex upright: the opening is on the viewer’s right. This is a dextral shell. The main plate shows the animal’s left profile instead.
Extended: head and foot project from the aperture. The operculum is carried on the foot.
The operculum is carried by the foot. It is not a hinged second shell. The two poses compare an extended body with a closed aperture; they do not encode exact withdrawal movements or timing.
Frontal teaching inset. Shell proportions, soft-part positions and plate shape are schematic. The opening remains on the same side in both states.
02 / Magnified grazing schematic
A ribbon with teeth.
A radula scrapes algal food from a surface. This enlarged open ribbon shows seven schematic teeth per displayed row, with approach, contact and a scraping return.
Approach the algal film
Illustrative stroke, tooth shapes and scale. The open ends show only a section of the ribbon; it is not an endless conveyor belt. Film and food marks explain the action without measuring feeding rate or rock erosion.
Eyes at the base.
One pair of tentacles explores the surroundings. The small eyes sit beside their bases. The main profile clearly shows the nearer eye; it does not invent eyes at the tips.
A protected pocket.
The single left gill sits inside the mantle cavity. The cutaway shows it in a pocket above and behind the head, with heart and kidney immediately behind.
Sources, drawing notes & toolkit credit
The exterior and opened body are original AI-generated natural-history illustrations, guided by original code geometry and inspected separately from the factual model. The internal painting is masked over the unchanged exterior, so anatomy is revealed in place. Frontal comparison and grazing study are original SVG geometry. Generated artwork is not anatomical evidence; relationships were checked against the university account.
This is an illustrative teaching study, not a specimen plate. Organ colours, proportions, tissue textures and cut planes are interpretive. The simplified left-side opening includes the deep right columellar muscle; no left duplicate is implied. Overlying tissues and reproductive anatomy are omitted. No exact dimensions, rates or mechanical timing are validated.
Made using Anatomy by Ryan (wheresryan22): SVG composition, figure/page frames and model/motion guidance. Our illustrations and adaptations imply no creator endorsement or scientific validation. About this collection and the upstream MIT licence.
- Richard Fox / Lander University: periwinkle anatomy — despite the heading, the laboratory-specimen section explicitly identifies the account and figures as Littorina littorea. Used to check organ relationships; its illustrations are not reproduced.
- MarLIN: common periwinkle — species form, conical shell, whorls, ridges, tentacles and uninterrupted aperture lip.
- Naturalis: Littorina littorea — shell and soft-animal descriptions.
- US National Park Service: periwinkle facts — muscular foot, grazing and operculum.
- Common periwinkle on Wikipedia — species overview.