Nereididae (formerly spelled Nereidae) are a family of

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

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

Characteristics

The

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

of Nereididae bears a pair of

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

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; plural: parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed ...

are mostly biramous (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 Giovanni Battista Cirri (1 October 1724 – 11 June 1808) was an Italian cellist and composer in the 18th century. Biography Cirri was born in Forlì in the Emilia-Romagna Region of Italy. He had his first musical training with his brother ...

. The first body segment with 1-2 pairs tentacular cirri without

acicula Acicula (singular: aciculum) are strong, stout internal chaetae that provide support to parapodia In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; plural: parapodia) refers to lateral outgrowths or protr ...

e. Compound

seta In biology, setae (singular seta ; from the Latin word for "bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. Th ...

e present.

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

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 (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its struc ...

, 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 (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

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 Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provid ...

and

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

, this is not mineralised with

calcium Calcium is a chemical element with the 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 ...

, 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 α-amino group (which is in the protonated –NH3+ form under biological conditions), a carboxylic acid group (which is in the de ...

rich protein, with bound

zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc 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 periodi ...

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

Systematics

Nereididae are currently considered a

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

taxon. Their closest neighbours in polychaete

phylogenetic tree A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...

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 ...

(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

* ''

Alitta ''Alitta'' is a genus of marine annelids in Nereididae family (commonly known as sandworms or ragworms). There are three recognised species within the genus, ''Alitta grandis'' (Stimpson, 1853), '' Alitta succinea'' (Frey & Leuckart, 1847) and '' ...

'' * '' Australonereis'' * ''

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 ...

'' * ''

Ceratonereis ''Ceratonereis'' is a genus of polychaete worms from the family Nereididae. Species The following species are assigned to ''Ceratonereis'': * ''Ceratonereis brunnea'' Langerhans, 1884 * ''Ceratonereis dawydovi'' ( Fauvel, 1937) * ''Ceratonereis ...

'' * '' Cheilonereis'' * '' Dendronereides'' * '' Eunereis'' * '' Gymnonereis'' * '' Hediste'' * '' Laeonereis'' * '' Leptonereis'' * '' Lycastopsis'' * '' Micronereides'' * '' Namalycastis'' * '' Namanereis'' * '' Neanthes'' ** '' Neanthes arenaceodentata'' * ''

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 on ...

'' * '' Nicon'' * '' Olganereis'' * '' Perinereis'' * ''

Platynereis ''Platynereis'' is a genus of marine biology, marine annelid worms that belongs to the Nereididae, a family of errant polychaete worms. The species ''Platynereis dumerilii'' is used in development biology to study development (embryogenesis), in ...

'' * '' Rullierinereis'' * '' Sinonereis'' * '' Solomononereis'' * '' Tambalagamia'' * '' Tylonereis'' * '' Tylorrhynchus'' * '' Unanereis'' * '' Websterinereis''

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 has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutri ...

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 whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...

s. Nereids only breed 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 reproductive episode before death, and iteroparous if it is characteri ...

) 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 reproduc ...

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

Human use

Ragworms such as '' Hediste diversicolor'' are commonly used as bait in sea

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

. They are a popular bait for all types of

wrasse The wrasses are a family, Labridae, of marine fish, many of which are brightly colored. The family is large and diverse, with over 600 species in 81 genera, which are divided into 9 subgroups or tribes. They are typically small, most of them le ...

and

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

. 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. lot ...

. Ragworms, such as '' Tylorrhynchus heterochaetus'', are considered a delicacy in

Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...

where they are used in the dish chả rươi.Nguyen Quang Chuong (2009)
Some contribution to study on productive charecteristics 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