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Dog Whelk

Nucella lapillus

The dog whelk is a small but highly specialized predatory sea snail found along the rocky shores of the North Atlantic, from the Arctic to temperate coastal waters. Its thick, spiraled shell varies in shape, thickness, and aperture size depending on wave exposure, with more robust shells developing in areas with stronger currents. A short, open siphonal canal extends from the base of its aperture, and while the outer lip of the aperture is thin in juveniles, it becomes thickened and toothed with age. These adaptations help the dog whelk withstand the harsh conditions of the intertidal zone, where it clings to rocks and mussel beds, enduring constant wave action and fluctuating tides.

As a carnivorous gastropod, the dog whelk feeds on barnacles, mussels, and other shelled invertebrates using two primary hunting techniques. It can force its long, tubular proboscis between the plates of barnacles or the valves of bivalves, using its rasping radula to tear away soft tissue. Alternatively, it drills a precise hole in the shell of its prey, secreting an acid to dissolve the calcium carbonate before inserting its proboscis through the opening. Once inside, the dog whelk releases a narcotizing secretion from its accessory salivary glands, immobilizing the prey. These glands also produce a cement-like substance that may help secure the proboscis to the prey's shell. The dog whelk then injects digestive enzymes into the prey’s body, breaking down its tissues into a nutrient-rich "soup," which it consumes.

Like other whelks, the dog whelk moves using a muscular foot that secretes mucus for gliding, and it possesses an operculum—a rigid plate that acts as a protective "trapdoor" when the snail retreats into its shell. Breathing is facilitated by a siphon, which allows the whelk to draw in oxygenated water even while partially buried in crevices. Female dog whelks lay clusters of eggs that attach to rocks or hard surfaces, each developing into a miniature version of the adult before hatching. By controlling populations of barnacles and mussels, the dog whelk plays a vital role in maintaining balance within the rocky shore ecosystem.

Fun Fact!

Dog whelks produce a natural acid that helps them bore holes into the shells of their prey!

Habitat & Range

Found along rocky shores of the North Atlantic, from the Arctic to temperate waters.

Lifespan & Growth

Can live up to 10 years, growing up to 4 cm long.

Role in Ecosystem

A key predator of barnacles and mussels, helping regulate intertidal populations.

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