Nereididae (formerly spelled Nereidae) are a family of

polychaete Polychaeta () is a paraphyletic class of generally marine Annelid, annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called c ...

worms. It contains about 500 - mostly-marine - species grouped into 42 genera. They may be commonly called ragworms or clamworms.

Characteristics

The

prostomium The prostomium (From Ancient Greek, meaning "before the mouth"; : prostomia; sometimes also called the "acron") is the Cephalization, cephalized first body segment in an annelid worm's body at the anterior end. It is in front of (but does not in ...

of Nereididae bears a pair of

palp Pedipalps (commonly shortened to palps or palpi) are the secondary pair of forward appendages among chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to the chelicera ...

s that are differentiated into two units. The proximal unit is much larger than the distal unit.

Parapodia In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; : parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed late ...

are mostly-

biramous The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments (called podomeres) are of Latin origin, and may be confused with terms for bones: ''coxa'' (meaning hip, ...

(only the first two pairs are uniramous).

Peristomium The peristomium is the first true body segment in an annelid worm's body in the anterior end. It is directly behind the prostomium and contains the mouth, tentacular cirri, and sometimes feeding palps, which may instead occur on the prostomium. If ...

fused with the first body-segment, with usually two pairs of tentacular cirri. The first body-segment with 1-2 pairs tentacular cirri without

acicula Acicula (: aciculum) are strong, stout internal chaeta A chaeta or cheta (; ) is a chitinous bristle or seta found on annelid worms, although the term is also frequently used to describe similar structures in other invertebrates such as art ...

e. Compound

seta In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae, ...

e are present.

Notopodia In invertebrates, the term parapodium (Greek language, Gr. ''para'', beyond or beside + ''podia'', feet; : parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in Annelid, annelids, where they ar ...

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 The pharynx (: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates ...

, 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 A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

(if present, they are usually branched and arise on mid-anterior segments of body). The

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

l body consists of four segments.

Jaw-material

Ragworms' teeth are made of a very tough, yet lightweight material. Unlike

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

and

tooth enamel Tooth enamel is one of the four major Tissue (biology), tissues that make up the tooth in humans and many animals, including some species of fish. It makes up the normally visible part of the tooth, covering the Crown (tooth), crown. The other ...

, this is not mineralized with

calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...

, but is formed by a

histidine Histidine (symbol His or H) is an essential amino acid that is used in the biosynthesis of proteins. It contains an Amine, α-amino group (which is in the protonated –NH3+ form under Physiological condition, biological conditions), a carboxylic ...

-rich protein, with bound

zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...

ions. Research on this material could lead to applications in engineering.

Systematics

Nereididae are currently considered a

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

taxon. Their closest neighbours in polychaete

phylogenetic tree A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA. In ...

are Chrysopetalidae and

Hesionidae Hesionidae are a family of phyllodocid bristle worms (class Polychaeta). They are (like almost all polychaetes) marine organisms. Most are found on the continental shelf; '' Hesiocaeca methanicola'' is found on methane ice, where it feeds on ...

(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 ''Ceratocephale'' is a genus of polychaetes belonging to the family Nereididae. The species of this genus inhabit marine and brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more sal ...

'' 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 ''Nereis'' is a genus of polychaete worms in the family Nereididae. It comprises many species, most of which are marine. ''Nereis'' possess setae and parapodia for locomotion and gas exchange. They may have two types of setae, which are found o ...

'' 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 An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize ...

but many are active

carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they ar ...

s. Nereids breed only once before dying (

semelparity Semelparity and iteroparity are two contrasting reproductive strategies available to living organisms. A species is considered ''semelparous'' if it is characterized by a single reproduction, reproductive episode before death, and ''iteroparous ...

), and most of them morph into a distinct form to breed (

epitoky Epitoky is a process that occurs in many species of polychaete marine worms wherein a sexually immature worm (the atoke) is modified or transformed into a sexually mature worm (the epitoke). Epitokes are pelagic morphs capable of sexual reprodu ...

). Ragworms are important food sources for a number of shore-birds.

Human use

Ragworms such as ''

Hediste diversicolor ''Hediste diversicolor'', commonly known as a ragworm, is a polychaete worm in the family Nereididae. It lives in a burrow in the sand or mud of beaches and estuaries in intertidal zones in the north Atlantic. This species is used in research, b ...

'' are commonly used as

bait Bait may refer to: General * Bait (luring substance), bait as a luring substance ** Fishing bait, bait used for fishing Film * ''Bait'' (1950 film), a British crime film by Frank Richardson * ''Bait'' (1954 film), an American noir film by Hugo ...

in sea-

angling Angling (from Old English ''angol'', meaning "hook") is a fishing technique that uses a fish hook attached to a fishing line to tether individual fish in the mouth. The fishing line is usually manipulated with a fishing rod, although rodless te ...

. They are a popular bait for all types of

wrasse The wrasses are a family, Labridae, of marine ray-finned fish, many of which are brightly colored. The family is large and diverse, with over 600 species in 81 genera, which are divided into nine subgroups or tribes. They are typically small, ...

and

pollock Pollock or pollack (pronounced ) is the common name used for either of the two species of North Atlantic ocean, marine fish in the genus ''Pollachius''. ''Pollachius pollachius'' is referred to as "pollock" in North America, Ireland and the Unit ...

. They are also used as fish-feed in

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...

. Ragworms, such as ''

Tylorrhynchus heterochetus ''Tylorrhynchus heterochetus'', also known as the Japanese palolo is a species of edible ragworm. The species can be commonly found in estuaries of the Yellow Sea, East China Sea and South China Sea. Its mature size is circa 5.65 cm. The worm ...

'', are considered a delicacy in

Vietnam Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of mainland Southeast Asia, with an area of about and a population of over 100 million, making it the world's List of countries and depende ...

where they are used in the dish

chả rươi ''Chả rươi'' (sand worm omelette) is a Vietnamese dish made from the polychaete worm '' Tylorrhynchus heterochetus''; it is a delicacy of some provinces in Northern Vietnam. The dish is prepared from live sand worms, which are put in hot wate ...

.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 called 禾虫 (Mandarin: Hé chóng, Cantonese: Woh4 chuhng4). They are harvested from the rice-fields and are often cooked with eggs.

References

*Santos et al., 200

*A Key to Families of Polychaete

*The City University of Hong Kong page on Nereida

*More Information on Nereidida

{{Taxonbar, from=Q1280602 Annelid families Phyllodocida