Veined Rapa Whelk
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.