Alitta Brandti in the Near Future
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Phylum: Annelida Neanthes brandti Class: Polychaeta, Errantia Order: Phyllodocida, Nereidiformia A clam bed worm Family: Nereididae, Nereidinae Taxonomy: Neanthes brandti has been stomial tentacular cirri (see Anterior append- placed in the genera Nereis and, most ages) (Blake and Ruff 2007). recently, Alitta. Depending on the author, Anterior: Prostomium short, broad and Neanthes is currently considered a separate not as long as peristomium (Fig. 2). The peri- or subspecies to the genus Nereis (Hilbig stomium is apodous and asetigerous. 1997). The genus Alitta was originally Trunk: Thick segments that are wider designated for the species, A. virens, based than they are long, gently tapers to posterior on parapodial morphology. Later, A. brandti (Fig. 1). was added to this genus. Although, most Posterior: Pygidium bears two slender authors regard Neanthes and Alitta as ventrolateral anal cirri (Fig. 1) (Blake and Ruff synonyms, there is evidence to suggest that 2007). Alitta is a monophyletic and a separate Parapodia: The first two setigers are unira- taxon to Neanthes (Bakken and Wilson mous. All other parapodia are biramous 2005). Currently, Neanthes brandti is the (Nereididae, Blake and Ruff 2007) where both name seen in local intertidal guides (e.g., notopodia and neuropodia have acicular lobes Blake and Ruff 2007), but this name could and each lobe bears 1–3 additional lobes change to Alitta brandti in the near future. (above and below) called ligules (Blake and Furthermore, N. brandti is one of three Ruff 2007). The posterior notopodial lobes species in a closely related cryptic species broadly expanded and leaf-like. All other complex which has been suggested to be lobes are small (Fig. 6). Dorsal cirri are short not three, but the single, widely distributed and inserted halfway along dorsal (notopodial) species – N. virens (Breton et al. 2004). lobe, while ventral cirri are inserted at the base of the neuropodial lobe (Fig. 6). The Description parapodia of epitokous individuals are modi- Size: Atokous or sexually immature individu- fied for swimming and are wide and plate-like als up to 185 mm in length, having 166 seg- (Hilbig 1997). ments. Epitokous (heteronereids) are 300- Setae (chaetae): Setae are compound and 600 mm in length, 18 mm in width, having can be blunt (falcigerous) or hair-like 230 segments (Hartman 1968; Fernald et al. (spinigerous) (Nereididae, Blake and Ruff 1987). 2007). Compound setae can be described as Color: Usually a dark iridescent green- heterogomph, meaning that the two basal brownish or blueish, with a ventrum more prongs are of unequal length, or homogomph, pale than dorsum (Hartman 1968). where basal prongs are of equal length (Fig. General Morphology: Thick worms that are 5). Notosetae are composite spinigers only rather wide for their length (Fig. 1). (Fig. 5) (Neanthes, Pettibone 1963; Fauchald Body: Individuals are flattened dorso- 1977; Hilbig 1997). Neurosetae are both ventrally and extremely active. Nereids are composite spinigers and short shafted recognizable by their anterior appendages falcigers (Fig. 5). including two prostomial palps and four peri- A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Hiebert, T.C. 2015. Neanthes brandti. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. Eyes/Eyespots: Two pairs of eyes in trape- (Blake and Ruff 2007). Neanthes species zoidal arrangement on prostomium (Fig. 2) have only homogomph spinigerous setae in (Nereididae, Hartman 1968; Blake and Ruff the posterior notopodia, a trait it shares with 2007). The eyes of epitokous individuals Hediste but without the fused falcigers. The are enlarged (Hilbig 1997). genus Neanthes is further distinguished by Anterior Appendages: Palps at sides of having only conical paragnaths on both pro- prostomium are thick at bases and each boscis rings, and biramous parapodia with have a small style (Fig. 2). The palps of composite setae (Hartman and Reish 1950). epitokous individuals are larger than sexual- Neanthes brandti has been at times ly immature individuals (Hilbig 1997). The considered a subspecies or a synonym of N. prostomium also bears two short and conical virens, the large, coldwater form (Breton et antennae (Fig. 2). Four pairs of smooth ten- al. 2004). This latter species, however, has tacular cirri are found on the peristomium only a few paragnaths on its proboscis rings, and second dorsal pair is the longest. (i.e. 2–3 rows in AreasmVII, VIII), not many Branchiae: Absent (Blake and Ruff 2007). as in N. brandti (4–5 rows in Areas VII, VIII). Burrow/Tube: Nereids secrete and live in The prostomium of N. virens is small and mucous-lined tubes (Hilbig 1997). triangular, its eyes are small and on the Pharynx: The pharynx bears a distinct ever- posterior half of the prostomium. It has short sible proboscis. The everted proboscis has antennae, and massive palps. These species two rings, oral (or proximal) and distal (or exhibit overlapping geographic distributions maxillary) and terminates with two fang- and it is possible that they are the same shaped jaws (Figs. 3, 4). The oral ring is species (Breton et al. 2004). used largely in burrowing, while the distal Neanthes succinea is one of the most ring is used in feeding (Barnes and Head common nereids in the NE Pacific, but is rec- 1977). Each ring is equipped with many pa- ognizable from N. brandti by its very pillae and conical paragnaths and their pat- enlarged posterior notopodial lobes, with a terns are taxonomically relevant. Area I is small distal dorsal cirrus attached at the end composed of three cones in tandem; Area II, of the lobe (Blake and Ruff 2007). Ill, IV are each with many cones in dense Furthermore, it has a heteronereid form and patches; Area V has zero to one cone N. limnicola does not. N. succinea is thought (Banse and Hobson 1974); Area VI has a to be a more southern form (although it has median row of four to five large cones; been reported from Netarts Bay). Areas VII and VIII are each with a broad Neanthes limnicola is usually pale and band of many cones (Hartman 1968) (N. translucent, not dark green and its posterior brandti has at least four to five rows) (Figs. parapodial lobes are not expanded like those 3, 4) (Banse and Hobson 1974). of N. brandti. Genitalia: Neanthes have spinigerous notosetae Nephridia: only (Hilbig 1997). The morphologically simi- lar genus, Nereis sensu stricto, is Possible Misidentifications characterized by species with spinigerous The prostomia of nereid worms are notosetae in the anterior half of the body and quite alike, with four eyes, a pair of frontal falcigerous notosetae posteriorly (Pettibone antennae and biarticulate palps, and 3–4 1963; Smith 1959). Common Nereis species pairs of tentacular cirri. The genus Nean- include the very abundant Nereis vexillosa, thes currently, includes 3–4 local species an olive green to brown worm found in many A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] diverse marine environments, especially in swarming and are attracted to night-lights in mussel beds. It has greatly elongated, strap June–August (Washington, Fernald et al. -like notopodial lobes in the posterior 1987). These epitokes provide observers with parapodia. Nereis eakini, from rocky one of the most spectacular displays of nereid habitats, has a long prostomium and swarming (Porch 1970). The sexually mature proboscis rings covered with small round (epitokous) animals swim wildly at night on paragnaths. The bright green Nereis grubei the water's surface, their medial parapodial has greatly expanded posterior notopodial lobes swollen for swimming. After expelling parapodial lobes and no paragnaths in Area sperm and eggs, the distended worms will V of the proboscis. Nereis procera is die. subtidal in sand, has tiny eyes, a very long Larva: The larval development of N. brandti is body, and unusually inconspicuous not known, and development varies in the Ne- paragnaths on its proboscis (Hartman reididae. Some species have embryos that 1968). The genus Nereis differs from are fertilized and develop in the plankton, Hediste because members of the latter while others develop in benthic egg masses. genus has 1–3 fused falcigers on the supra Their trochophore larval stage is usually re- -acicular bunch of posterior neuropodial duced and most nereids hatch as necto- setae (no local species are known, Blake chaetes (Fernald et al. 1987; Crumrine 2001). and Ruff 2007). Many larvae are lecithotrophic until their phar- ynx is fully developed. Finally, nereid larvae Ecological Information tend not to acquire many segments in the Range: Type locality is coastal Siberia. plankton, and instead do so once they have Known range includes northeast Pacific to settled into the benthos (Fernald et al. 1987). southern California (Hartman 1968). Juvenile: Local Distribution: Coos Bay distribution Longevity: includes sites along the South Slough in Growth Rate: Charleston (Hartman and Reish 1950). Food: Fecal castings, which are similar to the Habitat: Known habitats are highly variable lug worm (see Abarenicola pacifica), are small with individuals found in sand bars, thick and contain seaweed. Although some mud (Kozloff 1974), and Enteromorpha beds nereids are carnivorous (Blake and Ruff (MacGinitie and MacGinitie 1949). Largest 2007), many are herbivorous and use their specimens occur in fine mud and eelgrass jaws to tear apart and eat pieces of algae beds rather than in pure sand.