The Serpulidae are a family of sessile, tube-building annelid worms in the class Polychaeta. The members of this family differ from other sabellid tube worms in that they have a specialized operculum that blocks the entrance of their tubes when they withdraw into the tubes. In addition, serpulids secrete tubes of calcium carbonate. Serpulids are the most important biomineralizers among annelids. About 300 species in the family Serpulidae are known, all but one of which live in saline waters. The earliest serpulids are known from the Permian.
Serpulidae
Pecten sp. with serpulid worm encrusters; Duck Harbor Beach on Cape Cod Bay, Wellfleet, Massachusetts.
Ficopomatus enigmaticus
Filograna implexa
Polychaeta is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. More than 10,000 species are described in this class. Common representatives include the lugworm and the sandworm or clam worm Alitta.
Polychaete
Phyllodoce rosea
The Pompeii worm lives at great depths by hydrothermal vents at temperatures up to 80 °C
Hesiocaeca methanicola lives at great depths on methane ice