''Rapana venosa'', common name the veined rapa whelk or Asian rapa whelk, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of large

predatory Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

sea snail, a marine gastropod mollusc or

whelk Whelk (also known as scungilli) is a common name applied to various kinds of sea snail. Although a number of whelks are relatively large and are in the family Buccinidae (the true whelks), the word ''whelk'' is also applied to some other marin ...

, in the family

Muricidae Muricidae is a large and varied taxonomic family of small to large predatory sea snails, marine gastropod mollusks, commonly known as murex snails or rock snails. With about 1,600 living species, the Muricidae represent almost 10% of the Neoga ...

, the rock shells. This large sea snail has become an invasive species in many different localities around the world.

Shell description

The

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard o ...

of ''Rapana venosa'' is globose (rounded) and heavy, possessing a very short

spire A spire is a tall, slender, pointed structure on top of a roof of a building or tower, especially at the summit of church steeples. A spire may have a square, circular, or polygonal plan, with a roughly conical or pyramidal shape. Spires a ...

, a large body whorl, a strong

columella Lucius Junius Moderatus Columella (; Arabic: , 4 – ) was a prominent writer on agriculture in the Roman Empire. His ' in twelve volumes has been completely preserved and forms an important source on Roman agriculture, together with the wo ...

and a deep umbilicus. The

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An ...

is large and roughly ovate. Ornamentation is present externally as axial ribs, smooth spiral ribs ending in blunt knobs at both the shoulder and body whorl, and internally as small elongated teeth disposed along the outer lip margin. The external color varies from gray to reddish-brown, with dark brown dashes on the spiral ribs. Some specimens may have distinctive black/dark blue vein-like coloration patterns throughout the inner portions of the shell, usually originating from each individual tooth at the outer lip. A diagnostic feature for this species is the deep orange color found in the

and on the

. The height of the shell can reach up to 180 mm (about 7 in).

Distribution

This species is native to the marine and estuarine waters of the western Pacific, from the

Sea of Japan The Sea of Japan is the marginal sea between the Japanese archipelago, Sakhalin, the Korean Peninsula, and the mainland of the Russian Far East. The Japanese archipelago separates the sea from the Pacific Ocean. Like the Mediterranean Sea, i ...

Yellow Sea The Yellow Sea is a marginal sea of the Western Pacific Ocean located between mainland China and the Korean Peninsula, and can be considered the northwestern part of the East China Sea. It is one of four seas named after common colour ter ...

, East China Sea and the

Bohai Sea The Bohai Sea () is a marginal sea approximately in area on the east coast of Mainland China. It is the northwestern and innermost extension of the Yellow Sea, to which it connects to the east via the Bohai Strait. It has a mean depth of ...

. ''Rapana venosa'' is included in Russia's Red Book as threatened with extinction. The original known habitat for this species was the

Far East The ''Far East'' was a European term to refer to the geographical regions that includes East and Southeast Asia as well as the Russian Far East to a lesser extent. South Asia is sometimes also included for economic and cultural reasons. The ter ...

, but since 1947 it has been found in the

Black Sea The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Rom ...

, and its shell became a popular souvenir in

Crimea Crimea, crh, Къырым, Qırım, grc, Κιμμερία / Ταυρική, translit=Kimmería / Taurikḗ ( ) is a peninsula in Ukraine, on the northern coast of the Black Sea, that has been occupied by Russia since 2014. It has a pop ...

. Recently this species has been found as an exotic in the

Chesapeake Bay The Chesapeake Bay ( ) is the largest estuary in the United States. The Bay is located in the Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the Eastern Shore of Maryland / ...

, on the eastern coast of the United States.

Nonindigenous distribution

According to some authors, it appears to be the case that the spreading of this species outside its natural range has been made possible by the planktonic larval stage being transported along with

ballast water Ballast is used in ships to provide moment to resist the lateral forces on the hull. Insufficiently ballasted boats tend to tip or heel excessively in high winds. Too much heel may result in the vessel capsizing. If a sailing vessel needs to voy ...

in the hulls of ships, or that egg masses may have been transported with products of marine farming. Rapa whelks were first found in the

in the 1940s. Within a decade this mollusk had spread along the

Caucasian Caucasian may refer to: Anthropology *Anything from the Caucasus region ** ** ** ''Caucasian Exarchate'' (1917–1920), an ecclesiastical exarchate of the Russian Orthodox Church in the Caucasus region * * * Languages * Northwest Caucasian l ...

and

n coasts and moved into the Sea of Azov. From 1959 to 1972, its range extended into the northwest Black Sea, to the coastlines of

Romania Romania ( ; ro, România ) is a country located at the crossroads of Central, Eastern, and Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, Serbia to the southwest, Moldova to the east, and ...

Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedo ...

and

Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a transcontinental country located mainly on the Anatolian Peninsula in Western Asia, with a small portion on the Balkan Peninsula in ...

. These whelks have become established in the Adriatic and Aegean seas, and have also been found in the

Tyrrhenian sea The Tyrrhenian Sea (; it, Mar Tirreno , french: Mer Tyrrhénienne , sc, Mare Tirrenu, co, Mari Tirrenu, scn, Mari Tirrenu, nap, Mare Tirreno) is part of the Mediterranean Sea off the western coast of Italy. It is named for the Tyrrhenian pe ...

, on the Northern Atlantic coast of France, and the southeast coast of

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

, in

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

and the

Rio de La Plata Rio or Río is the Portuguese, Spanish, Italian, and Maltese word for "river". When spoken on its own, the word often means Rio de Janeiro, a major city in Brazil. Rio or Río may also refer to: Geography Brazil * Rio de Janeiro * Rio do Sul, a ...

estuary (including Samborombon Bay), and in

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

. In the United States the first specimen discovered was in August 1998 by members of the Virginia Institute of Marine Science (VIMS) Trawl Survey Group in Hampton Roads,

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...

. The species is now widely distributed and established in

. ''Rapana venosa'' is considered among the 100 worst

alien Alien primarily refers to: * Alien (law), a person in a country who is not a national of that country ** Enemy alien, the above in times of war * Extraterrestrial life, life which does not originate from Earth ** Specifically, intelligent extrater ...

species in Europe in the DAISIE European Invasive Alien Species Gateway,DAISIE European Invasive Alien Species Gateway
''Rapana venosa''
Last updated 30 October 2006, accessed 3 April 2010. one of two marine gastropods on the list. It is considered as about the 52nd the worst alien species in Europe.

Ecology

Habitat

Veined rapa whelks favor compact sandy bottoms, in which they can burrow almost completely. The native habitat of this species is a region of wide annual temperature ranges, comparable to other localities. Fleeing cold waters in the winter, this species may migrate to warmer, deeper waters, thereby evading cool surface waters. This fertile sea snail is extremely versatile, tolerating low salinities,

water pollution Water pollution (or aquatic pollution) is the contamination of water bodies, usually as a result of human activities, so that it negatively affects its uses. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. ...

and oxygen deficient waters.

Feeding habits

Veined rapa whelks are carnivorous selective

gastropods whose main diet consists of a variety of other mollusk species, mainly epifaunal bivalves such as

oyster Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not ...

s ('' Crassostrea virginica'') and mussels (''

Mytilus galloprovincialis The Mediterranean mussel (''Mytilus galloprovincialis'') is a species of bivalve, a marine mollusc in the family Mytilidae. It is an invasive species in many parts of the world, and also an object of aquaculture. Systematics ''Mytilus gall ...

'', '' Modiolus'' and '' Geukensia''), but also clams (''

Anadara inaequivalvis ''Anadara'' is a genus of saltwater bivalves, ark clams, in the family Arcidae. It is also called ''Scapharca''. This genus is known in the fossil record from the Cretaceous period to the Quaternary period (age range: 140.2 to 0.0 million y ...

'', '' Chamelea gallina'', '' Tapes philippinarum'', ''

Venus verrucosa ''Venus verrucosa'', the warty venus, is a species of saltwater clam. It is a species of marine bivalve mollusc in the family Veneridae, sometimes collectively known as the venus clams. Distribution This species is found around the European coas ...

'', and the northern quahog ''

Mercenaria mercenaria The hard clam (''Mercenaria mercenaria''), also known as the round clam, hard-shell (or hard-shelled) clam, or the quahog, is an edible marine bivalve mollusk that is native to the eastern shores of North America and Central America from Prince E ...

''). Prey are chosen by the whelk according to their species and size. Most snails feed by drilling a hole into their bivalve prey, but rapa whelks usually smother their prey by wrapping around the hinged region of the shell and feed by introducing their

proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elong ...

between the opened valves. The whelk can also secrete a thick

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It ...

that may or may not contain

biotoxin A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849– ...

s to weaken the prey. Shell drilling, however, is also not unknown in this species.

Life cycle

''Rapana venosa'' is dioecious, which means each individual organism belonging to this species is distinctly male or female. In this species' native range, mating occurs for extended periods of time, mainly during the winter and spring. It reproduces by

internal fertilization Internal fertilization is the union of an egg and sperm cell during sexual reproduction inside the female body. Internal fertilization, unlike its counterpart, external fertilization, brings more control to the female with reproduction. For inte ...

, after which it lays clusters of egg cases that resemble small mats of white to yellow shag carpet, mainly during spring and summer. One adult female can lay multiple egg cases throughout the season. Each cluster contains 50-500 egg cases, and each egg case may contain 200-1000 eggs. The pelagic

veliger A veliger is the planktonic larva of many kinds of sea snails and freshwater snails, as well as most bivalve molluscs (clams) and tusk shells. Description The veliger is the characteristic larva of the gastropod, bivalve and scaphopod ...

larvae (a larval form common to various marine and fresh-water gastropod and bivalve mollusks) then hatch, persisting in the water column for 14 to 80 days and feeding primarily on

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

. They eventually settle on the ocean floor where they develop into hard-shelled snails. Growth is rapid over the first year of life, and reproduction occurs from the second year onwards. Large specimens may be over ten years old.

Reasons for the survival of this invasive species

It is known that the abundance of prey, the lack of competition from other gastropod species, as well as the absence of direct predators of ''R. venosa'' may be some of the factors that contributed to the successful establishment of new populations of this sea snail outside its native range. The thick strong shell of the rapa whelk is arguably its strongest advantage over native whelks, because rapas can easily prey on local whelks, whereas local whelks are unable to successfully attack rapas. The thick shell also means that predators such as sea turtles are unable to feed on the invasive species, and can only feed on local whelk populations. It is suggested that once the rapa whelk reaches adulthood, it exists unchecked in the local population, and can consume and reproduce freely. The Veined rapa whelk is also highly tolerant to wide variations in salinity and oxygen concentration, a fact that may also help to explain its success as an invader of marine

coastal The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. The Earth has around of coastline. Coasts are important zones in ...

and

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estu ...

ecosystems An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

. In its native range ''Rapana venosa'' shows high temperature tolerance, being able to withstand temperatures varying from 4 to 27 °C (39.2 - 80.6 °F).

Impact of introduction

Veined rapa whelks have caused significant changes in the

ecology Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overl ...

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 Chesapeake Bay, so that scientists can develop a model that will define potential impacts to the Bay's ecosystem.

Imposex

The

imposex Imposex is a disorder in sea snails caused by the toxic effects of certain marine pollutants. These pollutants cause female sea snails (marine gastropod molluscs) to develop male sex organs such as a penis and a vas deferens. Imposex inducing subs ...

phenomenon has been observed in the veined rapa whelk in Chesapeake Bay. Imposex is characterized by the development of masculine sexual organs in female individuals as a consequence of exposure to organic tin compounds, such as

tributyltin Tributyltin (TBT) is an umbrella term for a class of organotin compounds which contain the (C4H9)3 Sn group, with a prominent example being tributyltin oxide. For 40 years TBT was used as a biocide in anti-fouling paint, commonly known as bo ...

(TBT). Such compounds are biocide and

antifouling Biofouling or biological fouling is the accumulation of microorganisms, plants, algae, or small animals where it is not wanted on surfaces such as ship and submarine hulls, devices such as water inlets, pipework, grates, ponds, and rivers that ...

agents, commonly mixed in paints to prevent marine encrustations on boats and ships. For this reason, it is not uncommon for high concentrations of such compounds to be present in the sea water near

shipyards A shipyard, also called a dockyard or boatyard, is a place where ships are built and repaired. These can be yachts, military vessels, cruise liners or other cargo or passenger ships. Dockyards are sometimes more associated with maintenance a ...

and docking areas, consequently exposing the nearby marine life to its possibly harmful effects. This unnatural development of male reproductive organs, however, has shown no negative effects on populations of this species, and no loss of reproductive capabilities of female ''R. venosa'' as a consequence of Imposex has been observed so far.

References

This article incorporates public domain text (a

public domain The public domain (PD) consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. Because those rights have expired, ...

work of the United States Government A work of the United States government, is defined by the United States copyright law, as "a work prepared by an officer or employee of the United States Government as part of that person's official duties." "A 'work of the United States Governmen ...

) from reference Myriah Richerson. 2008. ''Rapana venosa''.

USGS The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, a ...

Nonindigenous Aquatic Species Database, Gainesville, FL. Revision Date: 4/24/2006

External links

''Rapana venosa'' at Global Invasive Species Database

photo of eggs

Species Profile- Veined Rapa Whelk (''Rapana venosa'')
National Invasive Species Information Center,

United States National Agricultural Library The United States National Agricultural Library (NAL) is one of the world's largest agricultural research libraries, and serves as a national library of the United States and as the library of the United States Department of Agriculture. Located ...

. Lists general information and resources for Veined Rapa Whelk. {{taxonbar, from=Q139053 Gastropods described in 1846 Molluscs of Japan

venosa Venosa ( Lucano: ) is a town and ''comune'' in the province of Potenza, in the southern Italian region of Basilicata, in the Vulture area. It is bounded by the comuni of Barile, Ginestra, Lavello, Maschito, Montemilone, Palazzo San Gervas ...