The birds feed on ragworm, lugworm and other invertebrates. Common representatives include the lugworm ("Arenicola marina") and the sandworm or clam worm "Alitta". The lugworm or sandworm ("Arenicola marina") is a large marine worm of the phylum Annelida. There is a second species of UK lugworm "Arenicola defodiens" commonly called black lugworm. A lugworm lives in a U-shaped burrow in sand. Once it burrows into the sand a lugworm seldom leaves it. The buddy storyline follows the friendship of seagull Ollie and lugworm Quentin. Lugworm blood has a large oxygen carrying capacity which may have medical applications. Besides the seal the lugworm is probably the most famous animal in the Wadden Sea.