Rapana venosa

The shell of Rapana venosa is globose (rounded) and heavy, possessing a very short spire, a large body whorl, a strong columella and a deep umbilicus.

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.

[2] Veined rapa whelks are carnivorous selective predatory gastropods whose main diet consists of a variety of other mollusk species, mainly epifaunal bivalves such as oysters (Crassostrea virginica) and mussels (Mytilus galloprovincialis, Modiolus and Geukensia), but also clams (Anadara inaequivalvis, Chamelea gallina, Tapes philippinarum, Venus verrucosa, and the northern quahog Mercenaria mercenaria).

[3] It reproduces by internal fertilization,[14] after which it lays clusters of egg cases that resemble small mats of white to yellow shag carpet,[2][3] mainly during spring and summer.

[3] The pelagic veliger larvae (a larval form common to various marine and fresh-water gastropod and bivalve mollusks)[15] then hatch, persisting in the water column for 14 to 80 days[11] and feeding primarily on plankton.

[2] 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.

It is suggested that once the rapa whelk reaches adulthood, it exists unchecked in the local population, and can consume and reproduce freely.

[3] The Veined rapa whelk is also highly tolerant to wide variations in salinity and oxygen concentration,[11] a fact that may also help to explain its success as an invader of marine coastal and brackish ecosystems.

[3] Veined rapa whelks have caused significant changes in the ecology of bottom-dwelling organisms, and have become marine pests in the Black Sea.

Such compounds are biocide and antifouling 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 and docking areas, consequently exposing the nearby marine life to its possibly harmful effects.

Ventral (left) and dorsal (right) views of a shell of Rapana venosa
Apical view of the shell of Rapana venosa
Veined rapa whelk on the stamp of the Soviet Union
A shell of Veined rapa whelk, side by side with its egg case