Phyllodoce mucosa

The species is sometimes confused with Phyllodoce maculata so its precise range is unclear, but it is present in the Arctic Ocean, the North Pacific Ocean, the North Atlantic Ocean, the Gulf of Mexico, the North Sea, the Mediterranean Sea and the Black Sea. It is present on intertidal sand and mud flats, stones and shelly gravels, at depths down to about 20 m (70 ft).^[3]

Phyllodoce mucosa is a scavenger, carnivore and feeder on carrion. As mud and sand flats are uncovered during falling tides at night, the worms emerge from the sediment and move rapidly towards any dead animal, such as a mollusc, crab, or worm, lying on the surface. They can detect the corpse from 15 m (50 ft) or more. As each worm crawls it leaves a copious trail of mucus behind it and other worms are guided by this and form "roads" as they also move towards the carcass. There the worms suck at the dead tissue and may increase their body weight by a third before retreating back into the sediment.^[5]

At breeding time, swarms of mature adults form in surface waters. Females produce gelatinous egg masses containing more than 10,000 eggs which are attached to fronds of seaweed. The developing larvae pass through one or two trochophore stages and two further metatrochophore stages before settling on the seabed as larvae with five to nine segments. The larval stage lasts for up to about nine weeks.^[4]