Nassarius olivaceus

Lore & Background

The shell of Nassarius olivaceus is composed of eight or nine whorls, the lowest of which makes up nearly half the shell. It is smooth and slightly arcuated, often ornamented on each whorl with a whitish band. When young, the shell is marked with convex, longitudinal folds that are intersected at the base of the body whorl only by five or six deep transverse striae. On the upper whorls the folds are closer and more prominent than on the lowest, where they often disappear entirely.

The aperture is whitish, ovate, and notched at both ends, with an ash-colored cavity. The upper notch is small, placed on the upper edge of the outer lip, where it is contracted into a small canal. The basal emargination is arched. The outer lip is thick, margined exteriorly, indistinctly crenulated on the lower edge, and marked within with very distinct transverse striae. The left lip continues forward as a thin leaf that extends slightly over the columella; it is smooth interiorly and edged throughout with a row of small drops.

Reader's Guide

Nassarius olivaceus is a well-documented species within the Nassariidae family, noted for its distinctive shell morphology and wide distribution across the Indian Ocean and into the western Pacific. Its shell, ranging from 25 to 50 mm, exhibits a characteristic olive or reddish hue with a whitish band, and its sculptural details—such as the longitudinal folds and transverse striae—vary with age, providing useful taxonomic markers. The species has been recorded from numerous localities including East Africa, South Asia, Southeast Asia, and Australia, indicating a broad ecological range in tropical and subtropical marine environments.

The species has also been noted in parasitological studies, with Stephanostomum-like cercariae (Cercaria capricornia VII) reported from Australia. This connection highlights its role in marine food webs and parasite life cycles. The extensive synonymy and historical references—from Bruguière in 1789 through to Richmond in 1997—underscore its long-standing recognition in malacology. While not commercially prominent, the olivaceous nassa contributes to the biodiversity of mud snail communities and serves as a subject for systematic and ecological research.

Did You Know?

• The shell size varies between 25 mm and 50 mm.
• The shell is composed of eight or nine whorls, the lowest making up nearly half the shell.
• This species occurs in the Central and East Indian Ocean off Madagascar, Mozambique, South Africa, Mauritius, Tanzania, and many other locations.
• Stephanostomum-like cercariae from Australia, Cercaria capricornia VII, have been recorded as parasites of this species.