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A spire is a part of the coiled shell of molluscs. The spire consists of all of the whorls except for the body whorl. Each spire whorl represents a rotation of 360°. A spire is part of the shell of a snail, a gastropod mollusc, a gastropod shell, and also the whorls of the shell in ammonites, which are fossil shelled cephalopods.
Ecrobia ventrosa, common name spire snail, is a European species of small brackish water snail with a gill and an operculum, an aquatic gastropod mollusk in the family Hydrobiidae. [ 2 ] Distribution
Most authors figure the shells with the apex of the spire uppermost. In life, when the soft parts of these snail are retracted, in some groups the aperture of the shell is closed by using a horny or calcareous operculum, a door-like structure which is secreted by, and attached to, the upper surface of the posterior part of the foot. The ...
Peringia ulvae, commonly known as the Laver spire shell or mudsnail, is a European species of very small aquatic snail with gills and an operculum, a gastropod mollusk in the family Hydrobiidae. [ 2 ]
The snail's shell is reverse countershaded, because of its upside-down position in the water column. There is a light purple shade on the spire of the shell, and a darker purple on the ventral side. [9] The animal has a large head on a very flexible neck. The eyes are small and are situated at the base of its tentacles.
View of the spire side of the planispiral shell of the freshwater snail Anisus septemgyratus. This shell has seven and a half whorls A fossil shell of the marine gastropod Turritella communis. This shell has nine whorls. A whorl is a single, complete 360° revolution or turn in the spiral or whorled growth of a mollusc shell.
Apertural view of the shell of adult Tarebia granifera showing its pale brown body whorl and dark spire. View of the spire side of the planispiral shell of the freshwater snail Anisus septemgyratus. The body whorl is the outermost complete revolution of the shell spiral Three shells of the sea snail species Turritella communis.
The size of the shell varies between 45 mm and 105 mm. The imperforate, solid, thick shell has a strictly conical shape. The spire is more or less attenuated above. The apex is acute. The color of the shell is yellowish or grayish, more or less mottled and marbled with green or brown, the base is white, green or brown.