Neanthes virens (M. Sars, 1835)

Common name(s): Nereid worm, clamworm

Synonyms: Nereis (Neanthes) virens Neanthes virens
Phylum Annelida 
Subclass Errantia 
Order Phyllodocida 
Neanthes virens in a petri dish.
(Photo by:  Dave Cowles, July 2018)

Description:  Nereid worms (ragworms or clamworms, Family Nerididae) are motile polychaete worms. Their prostomium has a pair of palps which are differentiated into two units, the proximal of which is larger than the distal. They also usually have two prostomial  antennae. The peristomium is fused with the first body segment, and usually has 2 pairs of tentacular cirri.  The pharynx is eversible and has two regions. The distal region has one pair of strong jaws (photo). Varying numbers of scattered conical teeth (paragnaths) may be on both the distal and proximal regions of the pharynx (photo). The first body segment has 1-2 pairs of tentacular cirri which do not have aciculae. Some of the setae are compound. The notopodia are usually well-developed with flattened lobes. The notosetae are compound falcigers and/or spinigers (or rarely are absent). Most genera have no gills, but if gills are present they are typically branched and on some of the mid-sections of the body. Most are omnivores but some are active predators. They are semelparous (reproduce only once) and usually use epitokes for breeding. This species (Neanthes virens) has antennae and conspicuous palps on the prostomium. The peristomium has 4 pairs of tentacular cirri, which are not constricted into basal and distal units. All or nearly all of the paragnaths (teeth) on the everted pharynx are conical rather than elongated transversely, crowded into comblike rows, or otherwise different from conical. The proximal ring of the pharynx usually is well-covered by paragnaths, though they may be missing from area I. Areas VII and VIII of the pharynx has paragnaths arranged in 2-3 irregular rows. The first segment behind the prostomium has no setae. The notopodia of setigers have aciculae plus other setae. The dorsal  ligule of the parapodia is leaflike and much larger than the ventral  ligule (photo). The ventral cirrus of all parapodia is simple (not divided into two branches). Body segment 2 (which is directly behind the prostomium, or the peristomium itself) does not have a collarlike structure which extends around the prostomium. The notopodia on the posterior body do not have homogomph  falcigerous  setae. The body wall does not have prominent dark pigment bars. 

How to Distinguish from Similar Species:Neanthes brandti is very similar but has a band of 4 or more rows in areas VII and VIII of the everted pharynx. The ventral parapodial cirri on the anterior part of the body of Caratocephale loveni divide near the base into 2 branches. Cheilonereis cyclurus has a collar-like structure on body segment 2 which extends around the prostomium

Geographical Range:  Pacific and Atlantic

Depth Range:  Intertidal

Habitat:  Burrows in firm, sandy mud, making permanent tubes. Sometimes under rocks

Biology/Natural History:  This species may breed with or not be genetically isolated from Neanthes brandti. It breeds via epitokes on a lunar cycle. 



Dichotomous Keys:
  Carlton, 2007
  Kozloff, 1987, 1996 [as Nereis (Neanthesvirens]

General References:
  Ricketts et al., 1985

Scientific Articles:

Web sites:

General Notes and Observations: Locations, abundances, unusual behaviors:

Dorsal head
Dorsal view of the head, with eyes and 4 pairs of tentacular cirri on the prostomium. The pharynx with its anterior jaws and conical paragnaths can be seen partly everted from the peristomium ventral to the prostomium. Photo by Dave Cowles, July 2018.

Head ventral
This ventral view of the head shows the slightly everted pharynx with the distal jaws and paragnaths and rows of proximal paragnaths. Photo by Dave Cowles, July 2018

This ventral view shows the parapodia with the rounded posterior lobe .

Parapodia dorsal
In this dorsal view the blood can be seen circulating through the parapodia. Note also the long, leaflike dorsal ligules. Photo by Dave Cowles, July 2018

Dorsal parapodium with blood
This close-up dorsal view of the parapodium clearly shows the blood circulating through blood vessels. Photo by Dave Cowles, July 2018

Click HERE to see a movie of blood circulating in pulses through the dorsal vessel.

Authors and Editors of Page:
Dave Cowles (2018):  Created original page
CSS coding for page developed by Jonathan Cowles

Salish Sea Invertebrates web site provided courtesy of Walla Walla University