Lugworm Castings - Arenicola marina

Lugworms make U-shaped burrows with openings at both ends. Arenicola marina extrudes a pile of coiled castings (poop), while the similar species, A. cristata leaves a formless mound of castings. A lugworm spends most of its life in its burrow with its head at the bottom of the tunnel and its tail pointing up towards the surface. The worms feed on microorganisms found in sand and water. Any undigestible material passes through the worm, is ejected from the back of the burrow, and is what we call 'castings'.

Lugworms are important to tidal and beach ecosystems:

-The lugworms' burrowing helps to aerate the sand and its castings release nutrients back into the environment.

-They have an important role in the foodweb. They eat small organisms, help break down decaying matter, and are a food source for other animals. Predators, such as fish, crabs, and birds can attack lugworms when they come near the opening of their burrows to expel their castings. Lugworms have very fragile tails, which easily break off when attacked. This means that the predators end up with a tasty morsel, but the lugworm survives.

Habitat: Low tide pools