Nephtys ferruginea Hartman 1940

How to Distinguish from Similar Species: No other Nephytid has the dark longitudinal lines on both sides of the midline. Nephtys look similar to Nereis but have a different type of eversible proboscis and no long tentacles in the head region.

Sandworms burrow in sand or sandy mud

As with all members of family Nephtyidae, this species has few if any segments longer than wide, even when contracted. Its dorsal surface is not covered by paleae, elytra, or felt. It has no eyes, prostomial palps, nor radioles nor caruncle, no group of unbranched tentacles closely associated with the mouth, nor tentacular cirri on the peristomium. It does have 4 prostomial antennae, with the first pair arising at the anterolateral corners of the prostomium and the second pair on the lateral margins of the prostomium. This second pair may be divided into two branches. Nephytids also have a single cirrus at the posterior end of the body. Nephtys ferruginea has flattened and elongated interramal cirri, starting with setiger 3, which do not curve to the extent that they make a complete turn. Its everted pharynx has 22 rows of papillae. In life, it has several dark longitudinal lines on both sides of the midline of each segment.

Biology/Natural History: Little has been written about this individual species. Sandworms vary in color, and are often iridescent. They are usually predators, with an eversible proboscis. They are mostly active at night, and often may be found swimming then, in a sinusoidal motion. They burrow by everting their large proboscis, then withdrawing it and walking ahead into the space that opened up. They lack circular muscles so must evert the proboscis by contracting the longitudinal and perhaps dorsoventral muscles. They have unique, small spiral gills in the space between the notopodium and neuropodium on the parapodium. When burrowing the parapodia fold flat back against the body and the setae form a screen to keep particles out of the space around the gills. Strong cilia near the gills create a swift water current flowing backward along the body when burrowing. The genus has 4 small ocelli but they are invisible from the outside. The blood contains hemoglobin Although worms from genus Nereis and genus Nephtys look similar to one another, they are definitely different. One difference can be seen in the way they swim. Nephtys worms undulate their bodies only slightly while swimming and produce a strong forward propulsion by means of their parapodia, resulting in efficient forward swimming. Nereis worms, on the other hand, undulate their bodies strongly back and forth while swimming, similar to what they do while crawling but in a larger, metachronous wave which proceeds from the back to the front. This wave produces backward thrust which largely counteracts the forward thrust generated by the paddling parapodia, resulting in the worm mostly thrashing around rather than swimming efficiently forward.

Depth Range: Mid-intertidal to deep sea