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Nereididae Family Nereididae (nereidid/rag worm)
Phyllodocida (Annelida: Polychaeta)
About Family Nereididae polychaetes in New Zealand.  
How to recognise the family: Active, omnivorous worms, usually green or brown in colour, distinctive for the patterns of black chitinous denticles called paragnaths on the short eversible proboscis. Some species are very large. The head is rectangular to triangular with a pair of short antennae between a pair of jointed palps with stout bases, followed or surrounded by four pairs of long tentacular cirri. There are two pairs of large eyes. The proboscis is divided by a transverse groove into two parts and projects forward a pair of large, forcep-like jaws. The paragnaths on the proboscis vary in ornamentation, pattern, and presence or absence in a manner which largely defines the genera and species, although the presence of special types of chaetae and unusual parapodial development are also useful taxonomically. By convention, for ease of description of paragnath patterns, the proboscis surface is regarded as comprising eight areas identified by Roman numerals. The anterior part of the proboscis is called the maxillary ring and includes areas I-IV and the posterior part is the oral ring with areas V-VIII. An anal cirri pair is present. At sexual maturity most nereidid species metamorphose into a reproductive stage called a heteronereid. They develop enlarged eyes, enlarged anterior cirri, additional flattened parapodial lobes and paddle-like swimming chaetae, and are usually shortened considerably in length once fully metamorphosed. Males develop additional anal papilla structures for sperm release. Spawning takes place at night while free-swimming. Adult size: To more than 300 mm and 20 mm thick, although most adult nereidids are about 50-100 mm, and some are much smaller.
How to recognise the New Zealand genera: There are a large number of New Zealand nereidids including species of the following genera. Perinereis is the genus with most species described and has transverse area VI paragnaths which are smooth and elongate like bars. In genus Platynereis comb-like rows of paragnaths are present, especially on the maxillary ring. In Nicon and Websterinereis paragnaths are absent, but Websterinereis and Ceratocephale have inconspicuous papillae instead. Ceratonereis has paragnaths only on the maxillary ring. Parapodia have notopodial and neuropodial leaf-like lobes, and dorsal and ventral cirri. Ceratocephale has double ventral cirri and elongate dorsal cirri. Nereidid chaetae are compound spinigers and falcigers, usually with asymmetrical joints. In Platynereis and the large genus Nereis there are one or two stout, toothed falcigers with symmetrical joints (homogomph falcigers) amongst the notopodial spinigers. Nereis-like species without homogomph falcigers are usually placed in genus Neanthes, though the two genera are closely related. Micronereis, Namanereis and Namalycastis are relatively rare, often semi-terrestrial small nereids. They are usually without paragnaths and with reduced notopodia. Micronereis lacks antennae.
Quick pick shore species: Nereis falcaria (Willey, 1905) also has an unusual notched prostomium between the antennae. Nicon aestuariensis Knox, 1951 is a large species abundant in mud and fine sand along estuarine river banks. Perinereis nuntia (Savigny, 1818) is a very common species, tolerant of varied environments, often found burrowing in sand under stones in estuaries and sheltered beaches, sometimes in near-anaerobic conditions or reduced salinities. A small Ceratonereis species occurs in sand along the shore in low-salinity lagoons and estuaries. A Neanthes close to Neanthes multignatha (Wu, Sun & Yang, 1981) has recently been found in Hauraki Gulf soft substrata. The remainder of New Zealand nereidids are mostly found on hard substrata. Along the coast Platynereis australis (Schmarda, 1861) and some other as yet unnamed golden brown Platynereis species live in algal holdfasts and algal turf, as do the smaller Perinereis camiguinoides Augener, 1922, Nereis falcaria, Nereis ovarius Read, 1980, Neanthes cricognatha (Ehlers, 1904), and a small Websterinereis species.

The largest New Zealand nereidid, the muscular Perinereis amblyodonta (Schmarda, 1861), can be found almost dry in clefts and cracks high on the shore. Several other Perinereis species also live in crevices on rocky shores. Namanereis quadraticeps Blanchard, 1849 is a shore species known from the Subantarctic Islands and has been found very occasionally on the South Island coast. Micronereis minuta (Knox & Cameron, 1970, as Notophycus, family Notophycidae) is another small species known only from the Snares Islands intertidal. Namalycastis tiriteae Winterbourn, 1969, is found only in freshwater in the lower North Island. Few have been found, possibly because the species lives deep under layers of stone in rivers where digging is impossible.

Possible misidentifications: None; nereidids are probably the best known polychaetes of all.
Distributions, lifestyle, and habitat: Throughout New Zealand from freshwater and the upper intertidal to the deep sea offshore. Nereidids are rarely dominant in numbers compared to other polychaetes, but they are conspicuous due to their large size and vigorous movement. Nereidids are found in many habitats and not only on the sea-bottom. Gamete-filled heteronereids swarm in the sea on moon-less nights to seek mates and are attracted to lights in the same way as are night-flying insects.
Abundance: Moderately common to abundant.
Taxonomic note: There are no nereidids common in deeper offshore sediments although a Ceratocephale species occasionally is found, Hediste kermadeca Kirkegaard, 1995 has been recorded, and as yet undescribed nereidids have been found to be abundant in sunken logs trawled up from deep water. Cheilonereis peristomialis Benham, 1916, unique worldwide for its projecting peristomial collar, is a colourful commensal of large hermit crabs.
References: (Augener 1924a: p21-40, f7-16), (Augener 1924b: p316-356, f4-6), (Banse 1997: p123-124, P1.e-i), (Benham 1909: p242-244, P9.2-10), (Benham 1916: p39-393), (Benham 1950: p12-16, f3), (Day & Hutchings 1979: p105-111), (Ehlers 1904: p24-30, P3.10-20, 4.1-7), (Fitzhugh 1987: p174-183, f1-2), Glasby 1999:p100-103, f44), (Hutchings, Reid & Wilson 1975: p241-274, f1-18), (Hutchings & Turvey 1982: p93-144, f1-17), (Kirkegaard 1995: 32-33, f18), (Knox 1951a: p213-229, P44-50), (Knox 1960a: p115-124, f146-186), (Knox & Cameron 1970: p75,79-80, f1-5), (Read 1974: p1-214, f1-23), (Read 1980: p185-193, f1-2), (Schmarda 1861: p101-102, 107, P31.242, 246), (Wilson 1993: p241-252, f1-7), (Wilson & Glasby 1993: p253-277, f1-13), (Winterbourn 1969: p281-285, f1-7) (Wu, Sun & Yang, 1985: p163-164, f91).
(Full citations at Family pages literature cited list.)

Species in the guide: Rock Species: Nereis falcaria | Nereis ovarius | Perinereis amblyodonta | Perinereis camiguinoides | Perinereis pseudocamiguina
Sand Species: Ceratonereis Ceratonereis-A | Nicon aestuariensis | Perinereis vallata | Platynereis australis
Shell Species: None for this family.

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Last modified by G. Read, 25/07/2004    (dd/mm/yy)