Shell globose, with very large body whorl and low conical spire. Spire whorls with a strong shoulder, continued on the body whorl, and axial folds which make blunt knobs at their intersection with the shoulder; irregular spiral sculpture. Aperture large, ovate, slightly expanded, with thin outer lip with the edge fluted to match external spirals. Siphonal canal broad, widely open and bearing a series of scales.
grey to brownish with irregular darker blotches or flames, which tend to make an interrupted pattern on the cords. Aperture orange inside.
common size :
specimens from the Far East up to 180 mm, Mediterranean and Black Sea specimens usually less than 120 mm.
This species resembles the tropical Indo-Pacific species Rapana rapiformis. It is distinguished by having a higher spire with a shoulder rather than a keel, a heavier shell with inside of aperture bright orange; juveniles of R. venosa may have the interior of the aperture more distinctly fluted, more brownish, with dark streaks along the furrows. Another Indo-Pacific species, R. bezoar, is distinguished by a more scaly sculpture overall and a white aperture.
BIOLOGY / ECOLOGY
Clusters of egg cases about 30 mm high are individually attached to the substrate. Larvae hatch from there after 12-17 days and remain another 14-17 days in the plankton. Adults feed on bivalves and may be scavengers on carrion. Harding and Mann (1999) reported that R. venosa can open a clam by smothering the shell and introducing the proboscis between the gaping valve, without any drilling. It has become a major pest of oyster beds in the Black Sea. Growth is rapid over the first year of life (20 to 40 mm), reproduction occurs from the second ear onwards and large specimens may be over ten years old.
subtidal at 12-14 m depth (Aegean Sea); favours compact sandy bottoms, burrows almost completely, with only the siphon sticking out.