The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Rapana venosa
Rapana venosa
(veined rapa whelk)
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Rapana venosa

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.

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Nonindigenous Occurrences:

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.

StateYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†
Florida197319731Florida Bay-Florida Keys
Virginia199820006Hampton Roads; Lower Chesapeake Bay; Lower James; Lower Rappahannock; Lynnhaven-Poquoson; York

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.

Remarks: Rapana venosa was introduced into the Black Sea in the 1940's and within a decade spread along the Caucasian and Crimean coasts and to the Sea of Azov. Its range extended into the northwest Black Sea to the coastlines of Romania, Bulgaria and Turkey from 1959 to 1972. This species has been introduced and become established in the northern Adriatic and Aegean seas and is present at a location along the southeast coast of South America. 

So far, there has been no successful eradication of nonindigenous marine invertebrates in the United States.  Studies are under way at the Virginia Institute of Marine Science (VIMS) to help determine the whelk's spread and its potential environmental range.  VIMS researchers are interested in any sightings of this species in Virginia and Maryland waters. The institute is also paying watermen a bounty for live and dead whelks, because the goal is to find out where the whelk is spreading. Current studies are investigating the extraordinary reproductive habits of the snail.  In Hampton Roads, watermen and researchers have discovered the animals laying millions of egg cases. Potential for damage to native shellfish populations is present. The more scientists are learning about this species the more concerned they become about the region's seafood industry.

References: (click for full references)

Fales, R. - personal communication, 2015.

Author: Richerson, M., and A. Benson

Revision Date: 2/25/2015

Citation Information:
Richerson, M., and A. Benson, 2019, 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: 2/22/2019

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.

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Page Last Modified: Wednesday, October 10, 2018


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2019]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [2/22/2019].

Contact us if you are using data from this site for a publication to make sure the data are being used appropriately and for potential co-authorship if warranted. For queries involving fish, please contact Matthew Neilson. For queries involving invertebrates, contact Amy Benson.