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The Common Whelk (Buccinum undatum)

 
YouTube Video: "Whelk Facts: you might know whelk eggs!". Video: Animal Fact Files.

Contents

Introduction

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The common whelk (Buccinum undatum) is a large predatory sea snail found in cold and temperate waters of the North Atlantic, including the North Sea and parts of the western Baltic. It belongs to the family Buccinidae, known for their thick, spirally coiled shells and carnivorous lifestyle. With its robust shell and distinctive waved sculpture, the common whelk is well adapted to life in subtidal and deeper coastal zones, where it plays an important ecological role as both predator and scavenger. It is also of considerable economic importance in many northern countries, where it is harvested for food and traded internationally.

Taxonomy of Gastropoda: Clade Caenogastropoda: Buccinidae.
Whelks - scavengers that can drill into mussel shells!: Marine biologist Prof. Charles Griffiths speaks about the life and ecology of South-African whelks (Burnupena).

Distribution and Habitats

The common whelk is widely spread along the Atlantic coast from North America as far as Greenland, as well as in Europe from Norway to Brittany. It is usually found in shallow coastal waters, but can live as deep as 200 metres (~ 600 ft.). It usually prefers sandy or muddy substrates, where it stays burrowed in the ground during the day and goes out hunting during the night.

Historical und Cultural Importance

 
Common whelk (Buccinum undatum) off the Scottish coast.
Picture: Jim Greenfield (iNaturalist).
   
  Sipho einer Wellhornschnecke (Buccinum undatum)
A common whelk's (Buccinum undatum) sipho is not only used to provide
the snail with breathing water, but with a means to orient for food,
other whelks or enemies.
Picture: Peter Jonas, Unterwasser-Welt Ostsee.
Whelks have been collected and used as a food source since Prehistoric times. Archaeological finds from the Stone Age prove that coastal peoples used the robust shells as tools and even as simple muscial instruments. In later centuries the shells were also used as jewelry and decoration. Today, whelks are not only sought after as a culinary delicacy, but also are an important part of marine ecosystems, as well as an important indicator for the pollution of the oceans (see below).

Wikipedia: Buccinum undatum.
MarLIN UK: Common Whelk (Buccinum undatum).

Biology and Ecology

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Morphology and Anatomy

The common whelk (Buccinum undatum) has a sturdy, spirally coiled shell with typically 7 to 8 whorls. Shell coloration ranges from pale yellow to brownish-grey, often with darker bands or spots. The surface is prominently ridged, which strengthens the shell and helps the whelk withstand currents in the North Atlantic and North Sea.

The shell aperture is large and oval, featuring a distinct siphonal canal through which the snail, by way of its siphon, an elongated funnel emerging from the mantle, is provided with breathing water. On one hand, this allows the snail to obtain oxygen, on the other the snail is able to detect chemical cues in the water. Specialized chemosensory organs in the mantle cavity, called osphradia, help the whelk locate food, find mates, and avoid predators. Using its siphon, the snail can determine the direction of such chemical signals.

As in all gastropods, the soft body consists of a head, a muscular foot, and a visceral mass or visceral sack, covered by mantle tissue and completely enclosed within the shell. When it is active, the whelk extends its head and foot; at the head are two tentacles that cannot be retracted, with eyes situated at their base - unlike most land snails, which carry their eyes at the tips of their tentacles.

The whelk feeds using a typical gastropod radula - a ribbon-like tongue covered in rows of chitinous teeth - to rasp and tear food such as bivalves or carrion (see below).

The muscular foot is used not only for locomotion but also to help the snail keep its position in the sediment of the intertidal zone. The whelk even make use of its foot to subdue bivalves (see below). At the rear end of the foot is the operculum, a horn-like protective plate that closes off the shell aperture when the animal retreats into its shell, providing an effective defense against predators.

Reproduction and Development


A common whelk (Buccinum undatum) laying eggs.
Picture: Ron Offermans. 		 
The common whelk (Buccinum undatum) is dioecious, meaning that individuals are either male or female, and the sexes are easily distinguishable.

 When reproduction takes place, depends on the water's temperature: in colder northern waters, mating happens in spring when temperatures begin to rise, while in warmer European seas, mating takes place in autumn, as the water temperatures are cooler then and more favourable for the development of the young. During this time, the female releases pheromones to attract a mate.

Fertilisation takes place internally, which allows for the formation of protective egg capsules. These characteristic, balloon-shaped capsules are deposited by the female onto rocks or other hard substrates. Each capsule contains between 600 and 2000 eggs. Interestingly, the developing embryos within a single capsule may have different fathers, as female whelks can mate multiple times and store sperm until environmental conditions are optimal for egg-laying.

However, only a small number of juveniles will actually hatch. The others serve as a first food source for their older, more developed siblings. This type of development, in which the veliger larvae undergo their entire development within the capsule and hatch as miniature snails, is referred to as direct development - no free-swimming larval stage occurs. Some capsules may even be completely empty, serving only to protect the more centrally located capsules and the juveniles within.

SMITH, K.E. & THATJE, S. (2013): Nurse egg consumption and intracapsular development in the common whelk Buccinum undatum (Linnaeus 1758). Helgoland Marine Research 67 (1), 109-120. (Abstract).

The young whelks hatch after about five to six months, measuring just 3-4 mm in length. They begin feeding immediately, but grow relatively slowly: sexual maturity is usually reached only after about five years. If undisturbed by human influence, the life expectancy of acommon whelk is approximately 10 to 15 years.

Nutrition and Hunting Behaviour

  "Keep Your Valve Shut And You Might Live!"
Bivalves are remarkably good at detecting the presence of a common whelk. Mobile species such as scallops (Pectinidae) or razor clams (Pharidae) will attempt to flee as soon as a whelk is detected nearby.


Blue mussels with barnacles. Picture: Keith Hiscock, MarLIN.

Sessile species like blue mussels (Mytilidae), on the other hand, respond by keeping their shell tightly closed for as long as the whelk remains in the vicinity.
Common whelks (Buccinum undatum) are active predators and scavengers. Their diet consists mainly of bivalves, crustaceans, and other molluscs, but also includes sea urchins and polychaete worms. In the North Atlantic, polychaetes often make up about 60% of whelks' stomach contents.

Other marine gastropods, whose shell opening (aperture) is protected by an operculum (sometimes even other whelks), are attacked in a special way: the whelk drills through the shell wall of its prey using its radula. The drilling process is assisted by an acidic secretion produced by a special gland in its foot, which helps to dissolve the calcareous shell. Once the hole is complete, the soft body of the prey is consumed without resistance.

When subduing bivalves, whelks apply a different technique: they use their strong muscular foot to pull the shell valves apart. Sometimes, they even wedge the rim of their own sturdy shell between the valves like a lever. Once the valves are forced open, the bivalve is eaten quickly and efficiently. In fact, Buccinum undatum is surprisingly fast for a snail - a 2.5 cm cockle (Cardium edule) can be devoured in just 10 to 20 minutes.

Whelks also readily feed on carrion: groups of them are often found around fish waste on the sea floor. They may even follow sea stars to scavenge leftovers from their prey - often bivalves - or sift through the sediment the sea star dug up in search of food.

HIMMELMAN, J. H.  & HAMEL, J.R.  (1993): Diet, behaviour and reproduction of the whelk Buccinum undatum in the northern Gulf of St. Lawrence, eastern Canada. Marine Biology 116:3, pp. 423-430. (Abstract).
TAYLOR, J.D.  (1978): The diet of Buccinum undatum and Neptunea antiqua (Gastropoda: Buccinidae). Journal of Conchology 29, p. 309. (Abstract).
PRICE, N.R., HUNT, S. (1976): An unusual type of secretory cell in the ventral pedal gland of the gastropod mollusc Buccinum undatum L.. Tissue and Cell 8/2, pp. 217-228. (Abstract).

Distribution and Habitats

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Two whelks (Buccinum undatum) on the British southern coast.
Picture: Tamsyn Mann (iNaturalist).		  
The common whelk (Buccinum undatum) is widely distributed across the cold and temperate zones of the North Atlantic. Its area of distribution extends from the eastern coast of North America and Greenland to the shores of northern and western Europe - including Norway, the North Sea, the British Isles, and the French Atlantic coast, as well as eastward into the western Baltic Sea. Whelks are particularly abundant in the North Sea, the English Channel, and along the coasts of Scotland and Ireland. In the North, whelks are found until 85°N, in the South as far as 45°N.

MarLIN UK: Common Whelk (Buccinum undatum).

Whelks prefer sandy or muddy substrates near coastal areas but can also be found on rocky bottoms. They are most commonly found at depths between 10 and 200 metres, although specimens have been recorded from depths greater than 500 metres. In intertidal zones, they are rarely encountered, as they favour stable water temperatures and do not tolerate large thermal fluctuations well. Interestingly, juveniles and adults tend to inhabit different depths: younger whelks prefer shallower waters, while older individuals tend to migrate into deeper areas.

Wattwandern mit Johann: Dit un dat: Die Wellhornschnecke (In German).

Due to their relatively high salinity tolerance, common whelks can also survive in environments with fluctuating salt levels, such as fjords and estuaries. However, they prefer cold waters with salinities between 2 and 3%, and are rarely found in brackish areas with low salt concentrations.

Because of their affinity for cold water, common whelks are increasingly affected by rising ocean temperatures. In the southern parts of their range, populations have been declining in recent years, while in northern regions - such as along the coasts of Norway and Iceland - their numbers remain stable or even show signs of growth.

Ecological Importance

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This whelk's shell lid (operculum) is well visible: Nova Scotia, Canada.
Picture: Ian Manning (iNaturalist).
In the marine ecosystems of the northern seas, the common whelk (Buccinum undatum) plays an essential role. As a predatory gastropod, it is part of the complex benthic food web, influencing both the populations of its prey and the ecological balance of the ocean floor. Whelks primarily feed on bivalves, crustaceans, and other molluscs (see above), either by drilling through shells or by prying them open with the help of their muscular foot and reinforced shell rim. In doing so, they help regulate populations of species that could otherwise dominate the habitat, supporting a more balanced ecosystem.

Interestingly, whelks are capable of detecting weakened or injured animals by means of chemical signals in the water. Their osphradia - specialised chemoreceptors in the mantle cavity - allow them to locate prey precisely, ensuring that sick or damaged individuals are removed more quickly. This behaviour contributes to the overall health of marine populations.


Hermit crabs (Pagurus bernhardus: Oosterschelde, Netherlands)
often choose the left-over shells of whelks as a new home.
Picture: Adrie Rolloos (iNaturalist).		  
By digesting and excreting organic material, common whelks also support the remineralisation of the seafloor. The remains of their prey, along with their own waste, are broken down by bacteria and other microorganisms, serving as nutrients for marine plants and algae.

In turn, whelks themselves are an important food source for various predators, including wading birds such as the oystercatcher (Haematopus ostralegus), as well as for certain fish and crustaceans. Even starfish prey on whelks: for instance, the spiny starfish (Marthasterias glacialis) feeds on mussels, other starfish, and also gastropods such as whelks. Since whelks have been observed to follow starfish to scavenge leftovers (see above), they must distinguish between harmless and predatory species using chemical cues like saponins to avoid becoming prey themselves.

Animal Diversity Web: Buccinum undatum.

Even after a whelk's death, their empty shells continue to contribute to biodiversity: They serve as valuable new homes for hermit crabs (e.g. Pagurus bernhardus) and other small benthic organisms, offering protection from predators and environmental stress.

Schutzstation Wattenmeer: "Wo ist Bernhard?" (In German).

Endangerment and Protection

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  Imposex: When Females Become Males

Imposex is a form of sexual disruption in marine snails caused by environmental pollutants, most notably the organotin compound tributyl tin (TBT). Affected females develop male sexual characteristics such as a penis and vas deferens, which can severely impair or even completely block their reproductive ability.

This effect is particularly pronounced in predatory marine gastropods like the common whelk (Buccinum undatum), making them valuable bioindicators for marine pollution. The degree of imposex observed in a population provides insights into the concentration of harmful substances in the surrounding waters.

Although TBT has been banned in most countries since the early 2000s, residues still persist in many marine ecosystems and continue to impact whelk populations significantly.
In marine research, whelks are regarded as important bioindicators of environmental pollution. They are particularly sensitive to hormone-like substances such as tributyl tin (TBT), which was once widely used in antifouling paints on ships. TBT causes female whelks to develop male sexual characteristics - a phenomenon known as imposex. In heavily polluted areas, this often leads to infertility, which can result in the collapse of entire populations. The occurrence of imposex is therefore seen as a clear indication of chemical pollution in marine ecosystems and is used worldwide in environmental monitoring.

Overfishing and Environmental Problems

In addition to chemical pollution, whelks are also threatened by overfishing. In many coastal regions, they are considered a culinary delicacy (see below) and are either caught as bycatch or targeted directly. Intensive harvesting, often carried out without sustainable management plans, has led to notable declines in populations in some areas. Additionally, marine ecosystems are being altered by climate change and ocean pollution. Rising sea temperatures and ocean acidification negatively interfere with the formation of calcareous shells, which are essential for the survival of whelks in the same way as all shell-bearing gastropods.

Protection Measures and Sustainability

Within the European Union, steps have been taken to severely restrict the use of TBT as an antifouling agent. Since its ban in 2008, signs of recovery have been observed in affected whelk populations. In the UK and Ireland, initial efforts have also been made to manage whelk fisheries sustainably, through catch quotas and marine protected areas. In the long term, however, only a more conscious use of marine resources and stronger protection of whelk habitats will be able to secure their populations.

BUND: Die Wellhornschnecke, eine geduldige Jägerin (In German).

Historical and Cultural Importance

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The whelk has played a notable role in human history. Archaeological finds support the use of robust whelk shells as tools and ornaments. Also, there is evidence that shells were transported over long distances, both by people living at the coast, as well as by traders.

In some cultures, the solid and often beautifully spiralled shells of the whelk served as natural tools - they were used as spoons, water containers, or even as signal horns. Similar to the larger tropical triton shells (e.g. Charonia tritonis), it was possible to produce a booming sound by blowing into the aperture, which could be heard over great distances. In Norse mythology, the sound of a snail horn was associated with the calls of sea giants.

Unlike the dog whelk (Nucella lapillus), however, the common whelk (Buccinum undatum) cannot be used to produce dye.

 
Common whelk (Buccinum undatum): Nova Scotia, Canada.
Picture: Ian Manning (iNaturalist).
   
 
Cooked whelks (Bulots cuits) in Normandy. Picture: Wikipedia.nl.
In the Middle Ages, the whelk in some regions was regarded as a remedy for various ailments. A tincture was made from crushed snail flesh or powdered shell, which was used to treat respiratory issues and skin conditions. Though this medicinal use has largely been forgotten, it reflects the historical importance of the species.

Wist je dat? (Did You Know This?)

In the Netherlands, the common whelk is known as wulk, while in Flanders - especially when cooked - it is commonly referred to as karakollen. This name likely derives from the Spanish word caracoles, which simply means "snails".


 Wulloks (karakollen), a traditional seafood snack in Oostende (Flanders, Belgium). Picture: Sandra Fauconnier.

The term dates back to the period of the Spanish Netherlands (16th to 18th century), when the region was under Iberian influence.

To this day, karakollen are traditionally cooked and sold in clay pots at Flemish markets - a culinary link to the past!		  
In many European coastal regions, the whelk - known in French as bulot or buccin, and in English as whelk (see above) - has long been considered a delicacy. Especially in France, the UK and Ireland, it has traditionally been part of the local cuisine. It is usually prepared by boiling or steaming, often served with garlic butter or herbs. Beyond its culinary value, whelk shells were also appreciated as trade goods. In the coastal markets of north-western Europe, they were a common item and were exchanged or sold alongside other seafood.

Wikipedia.nl: Buccinum undatum (In Dutch).
Nieuwsblad: ‘Karakollen’ zijn écht Antwerps (In Dutch).

Economic Use

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While whelks were once mostly caught as bycatch in coastal fisheries or collected in intertidal zones (see above), there are now efforts to cultivate these snails in water farms (aquaculture). Initial trials have shown promising results, particularly with regard to sustainable production and the protection of wild populations. The main advantage of aquaculture lies in the ability to control water quality and food supply, resulting in faster growth and higher meat quality.

FAO: Whelk (Buccinum undatum): A page by the UN Food and Agriculture Organization (FAO) with data on distribution and fishery numbers of common whelks.
NIELSEN, J.W., Rønfeldt, J.L. (2022): "Appraisal of a novel fishery of whelks (Buccinum undatum) in Danish Waters". Regional Studies in Marine Science 56. (Link).

In the kitchen, whelk meat is considered a delicacy. Its mildly salty, nutty flavour is appreciated in many coastal regions. In France and the UK especially, whelks are a regular feature on seafood menus. In France and Flanders, they are traditionally boiled or served with garlic butter. On the British Isles and in the Netherlands, whelks are often pickled in vinegar and eaten as a snack.

The renowned British celebrity chef Rick Stein, known for his seafood creations, has even featured "whelk spring rolls" on his menu - a modern take on the classic spring roll, combining tender whelk meat with fresh herbs and vegetables. His aim is to show that whelks are not limited to traditional vinegar-and-salt preparations but can also shine in contemporary dishes.

Unsung Seafood: Rick Stein tries Jack's Whelk Springrolls.

Whelk meat is also a popular food in Asia, especially in Korea and Japan, where it is used in a variety of dishes.

Economic use of marine snails: Whelks.

Conclusion

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The common whelk (Buccinum undatum) is one of the largest and best-known marine snails in European waters, with a range extending as far as Canada and Greenland. A predatory species with impressive hunting behaviour, it preys mainly on other snails and bivalves. At the same time, it serves as prey for many animals, such as oystercatchers and sea stars. Its sturdy shell allows it to thrive at various depths in the Atlantic, North Sea and Baltic Sea - but pollution from substances like tributyl tin has severely impacted its populations. This has made the whelk an important indicator of the health of marine habitats.

At the same time, it is a culinary delicacy that has been valued for centuries in coastal regions of Europe. Growing demand for sustainable seafood could open up new possibilities for whelk aquaculture - an exciting development that may help reconcile conservation and use. A responsible approach to managing these animals is essential to secure their long-term survival and to protect marine ecosystems from further harm. In this way, the common whelk stands as a symbol of the need to use marine resources with respect and care.

 

Latest Change: 25.09.2025 (Robert Nordsieck).