Lugworms

Lugworms are marine worms in the polychaete family Arenicolidae, most commonly belonging to the genus Arenicola. The best-known species is Arenicola marina, the common lugworm, which inhabits shallow sands and muds along temperate coastlines. Related species occur across European, North American, and other temperate littoral zones.

They are burrow-dwelling animals that construct smooth, U-shaped burrows in soft substrates. The worm extends part of its body out of the tunnel to feed, drawing in sediment and extracting organic matter. The indigestible material is cast back onto the surface as distinctive worm casts, which can be seen around the burrow.

Lugworms are elongated, cylindrical worms with numerous segments and bristles (chaetae). They have a distinct anterior region and a tapered posterior end, and sizes vary by species, with individuals commonly reaching several centimeters to tens of centimeters.

Ecologically, lugworms contribute to sediment turnover and aeration, influencing nutrient cycling in coastal ecosystems. They are prey for shorebirds, fish, and crustaceans, and their presence can indicate sediment quality. Their populations respond to changes in pollution levels, salinity, and dissolved oxygen in coastal habitats.

Reproduction involves seasonal spawning with the release of eggs and sperm into the water column and external fertilization. Larvae develop as free-swimming trochophore stages before settling as juveniles in the sediment.

Human relevance centers on their use as fishing bait in many regions. Harvesting can affect local populations, so management measures exist in some areas. Beyond bait, lugworm activity supports sediment health and coastal ecosystem functioning.