paucispiral

Paucispiral is an adjective used in zoological morphology, especially in malacology and paleontology, to describe shells or shell-like structures that have only a small number of twists or whorls in their spiral. The term is relative, applied to individuals or taxa whose coiling is reduced compared with related forms that exhibit many whorls. It is commonly used in descriptive taxonomy to differentiate shell shapes and to aid in the identification of fossils and living mollusks.

The word combines Latin paucus, meaning few, with spiral, referring to the spiral arrangement of the shell. Because there is no universal fixed count for what constitutes paucispiral, the term is relative to the typical morphology of the group being described. It is often used in contrast to multispiral shells, which have many whorls, and planispiral shells, where the whorls are arranged in a single plane.

Paucispiral descriptions appear in taxonomic descriptions of both fossil and extant species. They can reflect evolutionary history, developmental constraints, or ecological adaptations that limit the accumulation of whorls. As a descriptive term, paucispiral provides a concise way to communicate shell morphology without prescribing a specific numerical threshold.

See also: spire, whorl, planispiral, multispiral.