Latin name: Arenicola marina
Global Distribution: Shores of western Europe, Norway, Spitzbergen, Siberia and Iceland. Western Atlantic from Greenland and along the northern coast from Bay of Fundy to Long Island
UK Distribution: All British and Irish shores
Size: 31cm long, rarely above 13cm in UK and 23cm in Europe. 1cm diameter
Diet: Microorganisms and dead organic matter (detritus) in the sediment.
Habitat: Intertidal mud and sand from higher to lower shore. Abundant in sheltered estuaries.

Arenicola marina is a large polychaete worm with a cylindrical segmented body (like all annelids) separated into three main parts, a head, thoracic region and abdomen. The head is small with no eyes or any appendages (e.g. antennae, limbs). The thoracic region consists of 19 segments bearing appendages and bristles, as well as external gills on the last 13 segments. The abdomen segments lack hairs or gills and is narrower than the thoracic region.

Lugworms spend most of their lives in U or J shaped burrows, around 20-40cm deep, out of which they defecate sediment cast onto the surface of sandy beaches. They can be vulnerable while defecating at the surface with their predators, such as flatfish and wading birds, sometimes catching them off guard. They burrow by pushing their head against the sediment, which is then kept loose by a water current driven through the burrow. They may make a fresh burrow specifically for a 2 day breeding period in October. The eggs are contained in tongue shaped masses of jelly anchored to the shore at one end. As the larvae develop they feed on this jelly and eventually break out as juveniles that burrow into the sediment.

Fun facts

  • This species is familiar to anglers as they use them as bait for their hooks.
  • Lugworms have featured occasionally in popular culture such as in a comic strip called “Ollie and Quentin” featuring a seagull (Ollie) and a lugworm (Quentin).
  • Their feeding on microorganisms and dead organic matter (detritus), leaves Arenicola marina vulnerable to consuming microplastics buried in the sediment (mud, sand etc).