Veined Rapa Whelk
(Rapana venosa)

Description: The orange colored surface of the large aperture, which contains small, elongate teeth, is the most notable feature of this whelk. The color of the heavily ribbed shell can vary from light gray to brown. Pronounced knobs form where the ribs meet the wide shoulder of the whorls. This whelk resembles our native whelk, the frilled dog winkle (Nucella lamellosa), but the relative size of the aperture is smaller in the dog winkle, and its maximum shell size is only 60 mm compared to 120 to 180 mm in the invasive whelk.

Habitat: Subtidally, on the sandy bottom areas of nearshore waters, bays, and estuaries. Veined Rapa whelks often buried themselves in the sand.

Origin: Sea of Japan, Yellow Sea, East China Sea, and the Gulf of Bohai.

Invaded Areas: North American East Coast: James River, Hampton Bar (Chesapeake Bay, Virginia). Europe: Mediterranean Sea, Black Sea, Aegean Sea, and Adriatic Sea.

Concerns: The Rapa whelk preys on bivalves such as oysters, clams, and mussels, and may also compete with them for burrowing space on sand flats. Temperature and salinity tolerance data suggest that Rapana venosa can successfully invade estuarine habitats as well as exposed shorelines. Because offspring originating from the same egg mass vary greatly in the amount of time spent before settling, some colonize locations near their parents while others end up far away. This capacity may result in rapid growth and spread of invasive populations, even when the number of founding adults is small.