| Nereididae | |
|---|---|
.jpg) | |
| Alitta succinea | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Annelida |
| Clade: | Pleistoannelida |
| Subclass: | Errantia |
| Order: | Phyllodocida |
| Suborder: | Nereidiformia |
| Family: | Nereididae Fauchald, 1977 |
Nereididae (formerly spelledNereidae) are a family ofpolychaete worms. It contains about 500 – mostly marine – species grouped into 42 genera. They may becommonly calledragworms orclam worms.
Theprostomium of Nereididae bears a pair ofpalps that are differentiated into two units. The proximal unit is much larger than the distal unit.Parapodia are mostlybiramous (only the first two pairs are uniramous).Peristomium fused with the first body segment, with usually two pairs of tentacularcirri. The first body segment with 1-2 pairs tentacular cirri withoutaciculae.Compoundsetae are present.Notopodia are distinct (rarely reduced), usually with more flattened lobes,notosetae compoundfalcigers and/orspinigers (rarely notosetae absent).They have two prostomialantennae (absent inMicronereis). Theirpharynx, 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 nogills (if present, they are usually branched and arise on mid-anterior segments of body). Thelarval body consists of four segments.
Ragworms' teeth are made of a very tough, yet lightweight material. Unlikebone andtooth enamel, this is not mineralised withcalcium, but is formed by ahistidine rich protein, with boundzinc ions.[1] Research on this material could lead to applications in engineering.[2]
Nereididae are currently considered amonophyletic taxon. Their closest neighbours in polychaetephylogenetic tree are Chrysopetalidae andHesionidae (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.
SubfamilyGymnonereidinae Banse, 1977[3]
SubfamilyNamanereidinae Hartman, 1959[3]
SubfamilyNereidinae Blainville, 1818[3]
Subfamily Nereididaeincertae sedis:[3]
Ragworms are predominantly marine organisms that may occasionally swim upstream to rivers and even climb to land (for exampleLycastopsis catarractarum). They are commonly found in all water depths, foraging in seaweeds, hiding under rocks or burrowing in sand or mud. Ragworms are mainlyomnivorous but many are activecarnivores. 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.[4]
Ragworms such asHediste diversicolor are commonly used asbait in seaangling.[5] They are a popular bait for all types ofwrasse andpollock. They are also used as fish feed inaquaculture.[6]
Ragworms, such asTylorrhynchus heterochetus, are considered a delicacy inVietnam where they are used in the dishchả rươi.[7]
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.
