The marine Sipuncula are regarded as consisting of 1 class, 4 families, 13 genera and 367 species and subspecies. Sipuncula are widespread in the benthos of the World Ocean: from 82" N and 77" S to the equator, and from the littoral to a depth of 7000 m; 63 % of the species are confined to the shelf. Temperatures tolerated range from -1.9 to 29 "C; however, most species are found within the 20 'C isotherm. The geographical distribution is confined to seas with normal oceanic salinity. The range for survival and reproduction is 27 to 44 9~ S. Sipuncula are mainly deposit feeders. According to the mode of feeding and motility, the Sipuncula comprise 4 ecological groups: (1) burrowers, indiscriminately swallowing the substratum; (2) worms hiding in vacant shelters and collecting detritus; (3) waiting sestonophages; (4) sessile worms, scraping off food from the substratum.

The present study deals with the species of Sipuncula collected from northern Cyprus in 1997 and 1998 by RV K. Piri Reis at depths ranging from 0 to 600 m. Faunistic analysis of the material yielded a total of 6 species and 5 subspecies belonging to four families  Golfingiidae, Phascolionidae, Phascolosomatidae, and Aspidosiphonidae, of which four species (Nephasoma (Nephasoma) constrictum, Phascolosoma (Phascolosoma) scolops, P. (P.) agassizii agassizii and P. (P.) stephensoni) are reported for the first time from the eastern Mediterranean. Among the habitats sampled, Posidonia oceanica and mud were represented by the highest number of species (6 species), followed by rocks (5 species) and Cystoseira crinita (5 species). Quantitative analysis of shallow-water benthic habitats indicated that sipunculan density in the area ranged from 25 individuals m-2 to 350 individuals m-2. According to the MDS analysis, there are two major species assemblages in the area, mainly structured by the types of habitats and depth.

The flatworm Stylochus tauricus Jacubova has been found associated with the barnacle Balanus improvisus Darwin, on which it feeds . The predation rate (the number of barnacles eaten by one polyclad in a month) ranges between 5-10 . Inside the empty shells of B. improvisus some egg-plates of S. tauricus were observed . Pelagic Gotte's larvae aged 2-3 days possess 4 lobes while those aged 7-8 days have 5 lobes . Flatworms can prey on the young of another species Balanus eburneus Gould, whereas predation on the mussels Mytilus galloprovincialis Lam . is rare. There is a direct correlation between predator abundance and prey ingested .

The bibliography concerning the Mediterranean Sipuncula is reviewed, particularly that from the eastern Mediterranean. Additional data are provided from macrobenthic samples collected between 1974 and 1997 in the Hellenic waters. A total of 17 species are recorded, five of which (Sipunculus norvegicus, Golfingia elongata, Nephasoma lilljeborgi, Thysanocardiacatharinae and Aspidosiphon (Akrikos) mexicanus) are reported for the first time in Hellenic waters. Three more species (Onchnesoma squamatum squamatum, Aspidosiphon (Aspidosiphon) elegans, Apionsoma (Apionsoma) trichocephalus) which are found exclusively in the extreme eastern basin (Israel, Egypt) raises the number of eastern Mediterranean Sipuncula species to twenty.

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