Nereididae (formerly spelled Nereidae) are a family of polychaete worms. It contains about 500 - mostly-marine - species grouped into 42 genera. They may be commonly called ragworms or clamworms.
Characteristics The prostomium of Nereididae bears a pair of palps that are differentiated into two units. The proximal unit is much larger than the distal unit. Parapodia are mostly-biramous (only the first two pairs are uniramous). Peristomium fused with the first body-segment, with usually two pairs of tentacular cirri. The first body-segment with 1-2 pairs tentacular cirri without aciculae. Compound setae are present. Notopodia are distinct (rarely reduced), usually with more flattened lobes, notosetae compound falcigers and/or spinigers (rarely notosetae absent). They have two prostomial antennae (absent in Micronereis). Their pharynx, when everted, clearly consists of two portions, with a pair of strong jaws on the distal portion and usually with conical teeth on one or more areas of both portions. Most genera have no gills (if present, they are usually branched and arise on mid-anterior segments of body). The larval body consists of four segments.
Jaw-material Ragworms' teeth are made of a very tough, yet lightweight material. Unlike bone and tooth enamel, this is not mineralized with calcium, but is formed by a histidine-rich protein, with bound zinc ions.Broomell et al. (2008) Cutting Edge Structural Protein from the Jaws of Nereis virens Biomacromolecules, 9 (6), pp 1669–1677. Research on this material could lead to applications in engineering.Marine Worm's Jaws Say 'Cutting-Edge New Aerospace Materials' Science Daily
Systematics Nereididae are currently considered a monophyletic taxon. Their closest neighbours in polychaete phylogenetic tree are Chrysopetalidae and Hesionidae (the superfamily Nereidoidea).
Nereididae are divided into 42 genera, but the relationships between them are as yet unclear. The family contains traditionally three subfamilies - Namanereidinae, Gymnonereinae and Nereidinae.
Genera
Subfamily Gymnonereidinae Banse, 1977Read, G.; Fauchald, K. (Ed.) (2023). World Polychaeta Database. Nereididae Blainville, 1818. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=22496 on 2023-10-27 Australonereis Hartman, 1954 Ceratocephale Malmgren, 1867 Dendronereides Southern, 1921 Gymnonereis Horst, 1919 Kinberginereis Pettibone, 1971 Leptonereis Kinberg, 1865 Micronereides Day, 1963 Olganereis Hartmann-Schröder, 1977 Rullierinereis Pettibone, 1971 Sinonereis Wu & Sun, 1979 Stenoninereis Wesenberg-Lund, 1958 Tambalagamia Pillai, 1961 Tylonereis Fauvel, 1911 Tylorrhynchus Grube, 1866 Typhlonereis Hansen, 1879 Websterinereis Pettibone, 1971
Subfamily Namanereidinae Hartman, 1959 Namalycastis Hartman, 1959 Namanereis Chamberlin, 1919
Subfamily Nereidinae Blainville, 1818 Alitta Kinberg, 1865 Ceratonereis Kinberg, 1865 Cheilonereis Benham, 1916 Composetia Hartmann-Schröder, 1985 Eunereis Malmgren, 1865 Hediste Malmgren, 1867 Imajimainereis de León-González & Solís-Weiss, 2000 Laeonereis Hartman, 1945 Leonnates Kinberg, 1865 Micronereis Claparède, 1863 Neanthes Kinberg, 1865 Nectoneanthes Imajima, 1972 Nereis Linnaeus, 1758 Nicon Kinberg, 1865 Paraleonnates Chlebovitsch & Wu, 1962 Parasetia Villalobos-Guerrero, Conde-Vela & Sato, 2022 Perinereis Kinberg, 1865 Platynereis Kinberg, 1865 Potamonereis Villalobos-Guerrero, Conde-Vela & Sato, 2022 Pseudonereis Kinberg, 1865 Simplisetia Hartmann-Schröder, 1985 Solomononereis Gibbs, 1971 Unanereis Day, 1962 Wuinereis Khlebovich, 1996
Subfamily Nereididae incertae sedis: Kainonereis Chamberlin, 1919 Lycastonereis Nageswara Rao, 1981
Ecology Ragworms are predominantly marine organisms that may occasionally swim upstream to rivers and even climb to land (for example Lycastopsis catarractarum). They are commonly found in all water depths, foraging in seaweeds, hiding under rocks, or burrowing in sand or mud. Ragworms are mainly omnivorous but many are active carnivores. Nereids breed only once before dying (semelparity), and most of them morph into a distinct form to breed (epitoky).
Ragworms are important food sources for a number of shore-birds.Animal Fact files: Ragworm (Nereis diversicolor) BBC Science & Nature
Human use
Ragworms such as Hediste diversicolor are commonly used as bait in sea-angling. They are a popular bait for all types of wrasse and pollock. They are also used as fish-feed in aquaculture.Merrit, Mike (13 January 2013) Sea-change as farm grows fish on land The Scotsman, Retrieved 22 January 2013
Ragworms, such as Tylorrhynchus heterochetus, are considered a delicacy in Vietnam where they are used in the dish chả rươi.Nguyen Quang Chuong (2009). Some contribution to study on productive characteristics of the palolo (Tylorrhynchus heterochaetus) Polychaeta - Nereidae in Hai Phong brackish water.
In rice-growing areas of China, these worms are harvested from the rice-fields and are often cooked with eggs.
In Thailand, ragworms have occasionally been reported in tap water supply systems in Chachoengsao Province. They are often broadly grouped with other marine polychaetes, and are commonly associated with members of the family Syllidae found in Bangkok water systems, which are locally referred to as tua roi khā (,) or tua Songkran (ตัวสงกรานต์, Songkran creatuares). They are frequently reported in tap water systems during the summer season, particularly around the Songkran festival period (13–15 April), which coincides with Thailand's hottest months.
References
Santos et al., 2006 A Key to Families of Polychaetes The City University of Hong Kong page on Nereidae More Information on Nereididae