Common name: veined rapa whelk
Synonyms and Other Names: Asian rapa whelk
Identification: Shell globose (rounded), has a very short-spired shell and large body whorl. The epidermal color varies from gray to reddish-brown, with dark brown dashes on the spiral ribs. Most specimens have distinctive black veins throughout the shell. A diagnostic feature for this species is the deep orange color found in the aperture and on the columella.
Size: can reach 180 mm (about 7 in)
Native Range: Marine and estuarine waters of the western Pacific, from the Sea of Japan, Yellow Sea, East China Sea and the Bohai Sea.
Hydrologic Unit Codes (HUCs) Explained
Puerto Rico &
Interactive maps: Point Distribution Maps
Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Rapana venosa are found here.
Table last updated 5/25/2018
† Populations may not be currently present.
Ecology: Veined rapa whelks are carnivorous gastropods whose main diet consists of a variety of other mollusk species such as native oysters. Most snails feed by drilling a hole into their prey, but rapa whelks smother their prey by wrapping around the hinged region of the shell and feeding between the opened valve. Reproduces by clusters of egg capsules, that resemble small mats of yellow shag carpet, and which produce pelagic larvae that eventually settle on the ocean floor where they develop into hard-shelled snails. Growth is rapid over the first year of life, reproduction occurs from the second year onwards and large specimens may be over ten years old. It favors compact sandy bottoms in which it can burrow almost completely. The native habitat is a region of wide annual temperature ranges, comparable to the Chesapeake Bay. Fleeing cold waters in the winter, this species may migrate to warmer, deeper waters, thereby evading cool surface waters. This fertile species is extremely versatile, tolerating low salinities, water pollution and oxygen deficient waters.
Means of Introduction: Possible ways of introduction include arrival in the Bay area as planktonic larvae in ballast water tanks of ships or that egg masses may have been transported with products of marine farming.
Status: Established in Chesapeake Bay. Adult specimens as well as egg cases continue to be reported from locations in the lower Chesapeake Bay.
Impact of Introduction: Veined rapa whelks have caused significant changes in the ecology of bottom-dwelling organisms, and have become marine pests in the Black Sea. Although scientists are not completely aware of the impacts of the whelk, they are very concerned about its potential impact on native Bay species. Studies are currently under way to help determine the whelk's spread in the Chesapeake Bay, so that scientists can develop a model that will define potential impacts to the Bay's ecosystem.
References: (click for full references)
Fales, R. - personal communication, 2015.
Richerson, M., and A. Benson
Revision Date: 2/25/2015
Richerson, M., and A. Benson, 2018, Rapana venosa: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=1018, Revision Date: 2/25/2015, Access Date: 11/19/2018
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.