''Arctonoe'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of worms in the family

Polynoidae Polynoidae is a family (biology), family of marine Polychaete worms known as "scale worms" due to the scale-like elytron (Annelida), elytra on the dorsal surface. Almost 900 species are currently recognised belonging to 9 subfamilies and 167 gen ...

. They are commonly known as "scale worms". Members of this genus predominantly occur in shallow (50 metres or less) waters of the north-eastern Pacific Ocean and often live as

commensals Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fro ...

of other marine invertebrates, frequently

echinoderms An echinoderm () is any animal of the phylum Echinodermata (), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". While bilaterally symmetrical as larv ...

but sometimes

molluscs Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

or other

polychaetes Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are m ...

Description

Arctonoe have long bodies, with 100 or more segments and numerous pairs of smooth translucent scales (

elytra An elytron (; ; : elytra, ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometime ...

) on several of the segments. The first segment (

prostomium The prostomium (From Ancient Greek, meaning "before the mouth"; : prostomia; sometimes also called the "acron") is the Cephalization, cephalized first body segment in an annelid worm's body at the anterior end. It is in front of (but does not in ...

), which contains the mouth, is rounded and smooth; on its side it has antennae pointing away from the body.

Parapodia In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; : parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed late ...

are found along the body with both dorsal (notopodial) and ventral (neuropodial)

acicula Acicula (: aciculum) are strong, stout internal chaeta A chaeta or cheta (; ) is a chitinous bristle or seta found on annelid worms, although the term is also frequently used to describe similar structures in other invertebrates such as art ...

penetrating

epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and Subcutaneous tissue, hypodermis. The epidermal layer provides a barrier to infection from environmental pathogens and regulates the ...

. The

notochaetae A chaeta or cheta (; ) is a chitinous bristle or seta found on annelid worms, although the term is also frequently used to describe similar structures in other invertebrates such as arthropods. Polychaete annelids (''polychaeta'' literally mean ...

are few in number and more slender than the

neurochaetae A chaeta or cheta (; ) is a chitinous bristle or seta found on annelid worms, although the term is also frequently used to describe similar structures in other invertebrates such as arthropods. Polychaete annelids (''polychaeta'' literally mean ...

both

and

have minutely notched tips (see Hanley, 1989 for detailed diagnosis).

Species

The following species are recognised in the genus ''Arctonoe'': *'' Arctonoe fragilis'' (Baird, 1863) *'' Arctonoe pulchra'' (Johnson, 1897) *''

Arctonoe vittata ''Arctonoe vittata'' is a species of scaled polychaete worms commonly known as a "scale worm". This species often lives as a commensal of another marine animal. Description At least thirty pairs of elytra, scale-like modifications to the dorsal ...

'' (Grube, 1855)

References

{{Authority control Polychaete genera Phyllodocida