Sipunculus nudus Linnaeus, 1766

Adrianov, Andrey V. & Maiorova, Anastassya S., 2012, Peanut worms of the phylum Sipuncula from the Nha Trang Bay (South China Sea) with a key to species, Zootaxa 3166, pp. 41-58 : 42

Sipunculus nudus Linnaeus, 1766

( Fig. 1 A )

Material. Nha Trang Bay: Mung Island, depth 14–15 m, muddy sand, 1 specimen; Kay River mouth, intertidal, 1 specimen; local fish-markets in Nha Trang, 10 specimens.

Description. Trunk 120–140 mm in length and 10–12 mm wide; introvert about ½ trunk length. Tentacular apparatus with four main branched stems, two dorsal 2 X as long as ventral pair. Longitudinal musculature splits into 28–32 bands. Nephridia partially (up to 50%) attached to the body wall; nephridiopores anterior to anus. Spindle muscle originates on body wall anterior to anus.

Discussion. The species is similar to S. robustus which differs by having unattached (free) nephridia.

This species is considered cosmopolitan in temperate to tropical waters. In the West Pacific it is found from New Zealand (Kermadek Islands) to Japan and is common in South China Sea, from South Vietnam to Hainan Island. Usually collected from the intertidal it has also been reported from depths of up to 2000 m. This species prefers muddy sand, mangroves and silty sediments.

Figures

FIGURE 1. A. Sipunculus nudus, dorsal view, introvert everted. B – D. Siphonosoma australe. B) lateral view, introvert retracted; C) head with tentacular apparatus; D) hooks. Scale bars: A – B, 10 mm; C, 3 mm; D, 0.3 mm.