Biomineralising polychaetes are polychaetes that biomineralize. The most important biomineralizing polychaetes are serpulids, sabellids and cirratulids. They secrete tubes of calcium carbonate. Serpulids have most advanced biomineralization system among the

annelid The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecol ...

s. Serpulids possess very diverse tube ultrastructures. Serpulid tubes are composed of aragonite,

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

or mixture of both polymorphs. In addition to the tubes, some serpulid species secrete calcareous opercula. Some sabellids and cirratulids can secrete aragonitic tubes. Sabellid and cirratulid tubes have a spherulitic prismatic ultrastructure. There are thin organic sheets in serpulid tube mineral structures. These sheets have evolved as an adaptation to strengthen the mechanical properties of the tubes.

References

{{reflist Polychaetes Serpulidae Biomineralization