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Gastropod

Dog Whelk

Nucella lapillus

Nucella lapillus (Linnaeus, 1758) · Muricidae WoRMS 140403

Reference photos

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A solid, broadly conical shell with about six swollen whorls, a short pointed spire dominated by the large last whorl, and low strap-shaped spiral ridges. A short, open siphonal canal runs from the base of the opening. Usually white, but grey, brown or yellow shells occur, sometimes with contrasting brown spiral bands; colour and banding appear to be under genetic control. It preys on barnacles and mussels, either forcing its proboscis between the plates or valves or boring a hole through the shell and digesting the animal inside.

Depth

Intertidal, from about mid-tide level downwards; only rarely in the shallow sublittoral

Size

Shell usually up to 3 cm high and 2 cm broad, reaching 6 cm in a few exceptional populations

Habitat

Rocky shores, wave exposed to sheltered: bedrock, boulders, crevices, overhangs and rockpools, among the barnacles and mussels it feeds on

Behaviour

A slow-creeping predator, most active at night and rarely moving far; gregarious, gathering in summer aggregations of 20 to 500 on open rock

Diet

I eat

  • Mainly barnacles and mussels, the sessile animals that hold space on a rocky shore
  • Cockles, other bivalves and other sea snails, taken less often
  • Acorn barnacles are the favoured prey ahead of mussels, and a whelk may still get through 15 to 40 mussels in a year

Eats me

  • Gulls and eider ducks swallow adults whole, and oystercatchers have caused heavy winter mortality; whelks of 4 cm or more are probably safe from birds
  • Crabs, which take the smaller ones: shore crabs handle whelks up to 1.5 cm long and velvet swimming crabs up to 2.5 cm
  • Small waders and rock pipits pick off the young, purple sandpipers favouring whelks only 2 to 5 mm long

Where you'd find it

Found around most of Britain and Ireland, though less often in the Celtic Sea and the waters west of Ireland.

ChannelCeltic SeaNorth SeaIrish SeaW of IrelandW of Scotland
Often seenNow and thenWhere PEBL filmsBased on marine survey records (OBIS). Blank seas can mean nobody has looked there, not that the animal is absent.

Sources

Open-access references behind this page. Every statement on this page was read out of one of them; anything that could not be traced to a source was taken off the page rather than left standing. Each link was checked on the date shown, and confirmed then to be about this species.

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