rapana

Rapana is a genus of large predatory sea snails in the family Muricidae. Members of this genus are carnivorous mollusks that prey primarily on bivalves, using their muscular foot to pry open shells and, in some cases, drilling holes with their radula and secretions. They inhabit coastal habitats on rocky and sandy substrates in temperate and subtropical waters.

The best-known species is Rapana venosa, the veined rapa whelk, native to the western Pacific, including the coasts of Japan, Korea, and China. The genus also includes other species distributed across the Indo-Pacific. In recent decades, Rapana venosa has become invasive in non-native regions, most notably the Black Sea and surrounding waters, where it preys on native mussels and oysters and has altered local benthic communities and fisheries. Some populations are also found in introduced ranges where commercial harvesting has developed.

Description of the shell: the shell is thick and heavy, elongate-conical, with strong axial sculpture and prominent varices. It is typically brown to reddish, often with darker veining or mottling that gives the veined appearance for which the veined rapa whelk is named. Shells can reach substantial sizes, commonly up to 10 to 15 centimeters in length.

Life cycle and ecology: Rapana species reproduce sexually, with females laying capsules that release free-swimming veliger larvae. The larvae disperse in the plankton before settling as juveniles, leading to potential rapid expansion in suitable environments. As predators of bivalves, they play a significant role in the ecology of infested regions and are a focus of management in areas where they are considered invasive.