Cirratulid polychaetes are abundant and diverse members of the benthic macrofauna and their particle collection mechanisms may strongly affect particle mixing and sediment grain size distribution in sediments. The feeding morphology differs in having a pair or many feeding tentacles and the ecological importance of both methods of food collection needs to be better investigated to understand their costs and benefits. Particle selection and feeding behaviour of a bitentaculate (Aphelochaeta honouliuli) and a multitentaculate species (Timarete hawaiensis) were comparatively observed. Feeding behaviour observations were done with individuals with or without feeding tentacles and exposed to three different size ranges of glass beads (0–20, 40–70 and 70–110 µm in diameter). Particle selection was tested for coated and uncoated glass beads of three different size ranges in 20 specimens of each species. Feeding behaviour was similar in both species and the methods of particle collection and ingestion are described. Individuals of T. hawaiensis, in which the feeding tentacles were removed, were observed collecting particles with the aid of branchiae. The multitentaculate species studied was more successful in collecting particles from greater foraging radii and at a faster rate than the bitentaculate species but the experimental design may have disfavoured the latter. Two-way ANOVA results showed that both bitentaculate and multitentaculate species significantly selected in favour of smaller particle sizes. Further studies about particle encounter, selection and ingestion are needed and may aid understanding of the phylogenetic relationships between the bitentaculate and multitentaculate cirratulids.

The cirratulid species Chaetozone corona is reported for the first time from the North-east Atlantic waters. Several specimens were collected during oceanographic surveys between 1996 and 2015 from soft bottom habitats along the coasts of Brittany (Western France). This species, originally described from the coast of California, was recently recorded for the first time from the Mediterranean Sea. We hypothesize that this species could have been recently introduced to the Atlantic coasts of Europe and colonized the northern coast of Bay of Biscay from the Loire estuary to the Iroise Sea. We discuss the potential vectors of introduction and the main environmental factors that could explain its current distribution. An identification key to all the known North-east Atlantic species of Chaetozone is given.

Oersted in 1843 gave a brief description of Dodecaceria concharum collected from the Kattegat. This was inadequate for identifying the species. Caullery and Mesnil in 1898 described three forms of Dodecaceria (A, B and C) but they were uncertain which form Oersted described. Dehorne in 1933 described D caulleryi (now D. fimbriata), which reproduce asexually, and Form B of Caullery and Mesnil. By default Form B became D. concharum the parthenogenetic species Form A of Caullery and Mesnil. Gibson and Heppell in 1995 in an attempt to consolidate these names deposited new types for the two species at the Cambers Street Museum in Edinburgh.

Assessing and monitoring the environmental impact off Mar del Plata (38°S 57°W) led to the need to identify the cirratulid polychaetes. Cirratulids are indicators of moderately impacted areas or early indicators of organic contamination. Some subtidal sand patches affected by sewage discharge have high abundances of a new, rare and difficult to place species, such as Caulleriella trispina sp. nov. This species is characterized by having characters of three bitentaculate cirratulid genera, including three kinds of spines: unidentate, sub-bidentate and bidentate. The genera and their taxonomic characters are discussed as well as the need for monitoring and environmental assessments for correct identification. A key to the known species from the warm-temperate region of Argentine Cirratulidae is given.

Cirratulus dollfusi Fauvel, 1928 is re-described from the material from the Sea of Marmara. The specimens collected from the Sea of Marmara were compared to the holotype of the species. The species is a multitentaculate and multibranchiate cirratulid; it differs from all other known cirratulid genera in its type of chaetae and the way the multiple branchial filaments arise from the notopodia. Chaetae are of two types: numerous long, fine capillaries in both rami throughout, also 2–4 shorter, wider, finely tapering spines in noto- and neuropodia. There are no slightly flattened sigmoid spines, typical of most Cirratulus species. Very short, slender grooved tentacles arise in a small circular group on either side of chaetiger 1. Branchial filaments are multiple; they arise as 1–2 filaments from each of 4–8 raised notopodial lobes on parapodia of anterior and middle segments, with lobes fading out and fewer (holotype) or no branchiae posteriorly (our material). No other cirratulid genera appear to have straight, tapering spines plus so many fine capillaries. We propose Fauvelicirratulus gen. nov. for this species. The species seems most closely related to Cirratulus hedgpethi Hartman, 1951, from the northern Gulf of Mexico, still only known from the incomplete original description. Features of some cirratulid genera are compared and the use of multiple branchiae as a generic character is discussed.