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. The body whorl is the outermost complete revolution of the shell spiral]] . The body whorl shows in this side view as the last complete turn of the shell spiral, the part of the shell that leads up to the aperture
Aperture (mollusc)

The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....
]]

Body whorl is a term applied to a snail
Snail

The word snail is a common name for almost all members of the molluscan class Gastropoda that have coiled animal shells in the adult stage. When the word snail is used in a general sense, it includes sea snails, land snails and freshwater snails....
 shell. It refers to part of the morphology
Morphology (biology)

The term morphology in biology refers to form, structure and configuration of an organism. This includes aspects of the outward appearance as well as the form and structure of the internal parts like bones and organs....
 of a coiled snail
Snail

The word snail is a common name for almost all members of the molluscan class Gastropoda that have coiled animal shells in the adult stage. When the word snail is used in a general sense, it includes sea snails, land snails and freshwater snails....
 shell, that of a shelled gastropod mollusk.

The body whorl is the most recently-formed and largest whorl
Whorl (mollusc)

File:Anisus septegyrus1pl.jpgFile:Turritella communis fossiel.jpgA whorl is a single, complete 360? revolution or turn in the spiral growth of a mollusc shell....
 (or revolution) of a spiral
Spiral

In mathematics, a spiral is a curve which emanates from a central point, getting progressively farther away as it revolves around the point....
 or helical shell
Gastropod shell

The gastropod shell is a seashell which is part of the body of a Gastropoda or snail. It is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage....
, terminating in the aperture
Aperture (mollusc)

The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....
.






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. The body whorl is the outermost complete revolution of the shell spiral]] . The body whorl shows in this side view as the last complete turn of the shell spiral, the part of the shell that leads up to the aperture
Aperture (mollusc)

The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....
]]

Body whorl is a term applied to a snail
Snail

The word snail is a common name for almost all members of the molluscan class Gastropoda that have coiled animal shells in the adult stage. When the word snail is used in a general sense, it includes sea snails, land snails and freshwater snails....
 shell. It refers to part of the morphology
Morphology (biology)

The term morphology in biology refers to form, structure and configuration of an organism. This includes aspects of the outward appearance as well as the form and structure of the internal parts like bones and organs....
 of a coiled snail
Snail

The word snail is a common name for almost all members of the molluscan class Gastropoda that have coiled animal shells in the adult stage. When the word snail is used in a general sense, it includes sea snails, land snails and freshwater snails....
 shell, that of a shelled gastropod mollusk.

The body whorl is the most recently-formed and largest whorl
Whorl (mollusc)

File:Anisus septegyrus1pl.jpgFile:Turritella communis fossiel.jpgA whorl is a single, complete 360? revolution or turn in the spiral growth of a mollusc shell....
 (or revolution) of a spiral
Spiral

In mathematics, a spiral is a curve which emanates from a central point, getting progressively farther away as it revolves around the point....
 or helical shell
Gastropod shell

The gastropod shell is a seashell which is part of the body of a Gastropoda or snail. It is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage....
, terminating in the aperture
Aperture (mollusc)

The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....
. It is called the "body whorl" because most of the body of the soft parts of the animal fits into this whorl.

In shelled cephalopod
Cephalopod

The cephalopods are the mollusc class Cephalopoda characterized by bilateral symmetry, a prominent head, and a modification of the mollusk foot, a muscular hydrostat, into the form of cephalopod arms or tentacles....
 mollusks such as ammonite
Ammonite

Ammonites are an Extinction group of marine animals of the Subclass Ammonoidea in the class Cephalopoda, phylum Mollusca. They are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific Geologic time scale....
s and nautilus
Nautilus

Nautilus is the common name of any marine creatures of the cephalopod family Nautilidae, the sole family of the suborder Nautilina....
, the equivalent space is known as the body chamber
Body chamber

The body chamber, also called the living chamber, is the outermost or last chamber in the Animal shell of a nautiloid or Ammonoidea cephalopod....
, although the term body whorl is also sometimes used.

The proportional size of the body whorl in gastropod shells differs greatly according to the actual shell morphology. For shells in which the rate of whorl expansion of each revolution around the axis is very high, the aperture and the body whorl are large, and the shell tends to be low spired
Spire (mollusc)

File:Turritella communis Turmschnecke.jpgFile:Little snail.JPGFile:Xerolenta obvia3pl.jpgFile:Planorbarius_corneus_top.jpgA spire is a descriptive term for part of the Animal shell of a snail, a gastropod mollusc shell or gastropod shell....
. The shell of the abalone
Abalone

Abalone are medium-sized to very large edible sea snails, marine gastropod mollusks in the family Haliotidae and the genus Haliotis....
 is a good example of this kind of shell.

The opposite tendency can sometimes create a high spire with very little whorl increase per revolution. In these instances, e.g. in the shell of Turritella
Turritella

File:Sea shells, playa grande, costa rica.jpgTurritella is a genus of medium-sized sea snails with an Operculum , marine gastropod mollusks in the family Turritellidae....
 species, both the body whorl and the aperture are relatively small.

In mollusc shells where there is no elevation at all to the spire, and only moderate whorl expansion, the body whorl can sometimes still represent a large part of the shell, e.g. in some species in the family Planorbidae
Planorbidae

Planorbidae, common name the ramshorn snails or ram's horn snails, is a family of air-breathing freshwater snails, Aquatic animal pulmonate gastropod mollusks....
, such as the genus Segmentina
Segmentina

Segmentina is a genus of small, air-breathing, freshwater snails, Aquatic animal gastropod mollusks or micromollusks in the family Planorbidae, the ramshorn snails....
.

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