Gallery_2_Veined Rapa Whelk | PA iMapInvasives

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Photo credit: George Chernilevsky - Own work, Public Domain

Veined Rapa Whelk

(Rapana venosa)

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Species at a Glance

The veined rapa whelk is a large predatory snail found in the Chesapeake Bay. Its main diet consists of natural and cultivated populations of mollusks, such as oysters and mussels. Because of its predatory impact, it is considered one of the most unwelcome invaders worldwide.

Identification

The heavy, rounded shell of this snail grows 15-18 cm (6-7 in) in length and is almost as wide as it is long, giving it a boxy appearance. It has a short spire and a large body whorl, and it varies in color from gray to reddish-brown with dark brown dashes on the spiral ribs. Most shells have distinctive black veins throughout. A diagnostic feature for this species is the deep orange color found on the inside of the shell.

Similar Species

The large size, deep orange color inside the shell, and distinctive black veins distinguish the veined rapa whelk from any other type of snail in the United States.

Habitat

This species is extremely versatile, tolerating low salinities, water pollution, and oxygen deficient waters. It favors compact sandy bottoms where it can burrow deep into the substrate.

Spread

The veined rapa whelk lays clusters of eggs that form into free-floating larvae that eventually settle on the bottom to develop into a hard-shelled snail. This species may have been introduced as the larvae were transported in the ballast water of ships, or as egg masses were transported with products of marine farming.

Distribution

Native to marine and estuarine waters of the western Pacific, from the Sea of Japan, Yellow Sea, East China Sea, and the Bohai Sea, the first veined rapa whelk specimen in the United States was collected in 1998 in Hampton Roads, Virginia. Adult specimens, as well as egg cases, continue to be reported from locations in the lower Chesapeake Bay along the western shore of Virginia.

Note: Distribution data for this species may have changed since the publication of the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016), the source of information for this description.

Environmental Impacts

The veined rapa whelk has caused significant changes in the ecology of bottom-dwelling organisms in its native range, and while scientists are still studying these impacts, there is great concern over its potential damage to native Chesapeake Bay species.