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Taxonomic information across the Internet

Eunicida

Rather than addressing a single family, this form will attempt to deal with a group of closely related families (Eunicidae, Onuphidae, Lysaretidae, Arabellidae, Lumbrineidae and Dorvillidae) which have similar features and are often confused by inexperienced workers. Ultimately, it is more useful to adopt this approach than to risk species being lost, by being allocated erroneously to the wrong family.

What does a Eunicida look like?

The following summary is based on that of Day (1967). These worms have elongate bodies with numerous segments. They are often tubicolous, the tube ranging from a mucus sheath to being tough and leathery. The head is always well developed and the peristomium and prostomium are usually distinct. Principal features are as follows:-

Palps: variable in form ranging from finger-shaped to globular. In some species, they are fused with the prostomium and are not readily identified.

Antennae: 0 to 7. Usually smooth but may occasionally be jointed or wrinkled. In some species, antennae arise from clearly ringed ceratophores.

Pharynx: muscular armed with dorsal pair of mandibles and a ventral series of toothed maxillary plates.

Tentacular cirri: there may be a single pair.

Parapodia : uniramous.

Dorsal cirri: sometimes present and may contain an aciculum.

Branchiae: sometimes present. In such species, the branchia are outgrowths of the dorsal cirri and may range in form from simple, cirriform to pectinate with spirally arranged filaments.

Ventral cirri: sometimes present.

Chaetae: a broad range of both simple and compound chaetae may occur.

What other families might be confused with Eunicids?

Nereidae: The Nereidae have biarticulate palps and biramous parapodia; jaws are less complex than those of eunicids but the reversible proboscis is covered by distinctive groups of chitinous paragnaths and/or soft papillae. Parapodia are biramous. (See Nereidae in Family Browser)

Hesionidae; some eunicids might possibly be mistaken for hesionids; these usually have biarticulate palps, and 6-8 pairs of tentacular cirri (rarely 2 pairs). Where chitinous jaws are present, these tend to be simple and are usually limited to no more than a single pair with a median tooth. The parapodia are either biramous or uniramous. (See Hesionidae in Family Browser)

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