with all Polynoids, this
species is mostly benthic, few if any of the segments are longer than
when contracted, the dorsal surface has clearly visible elytra,
and all of the neurosetae are simple. Arctonoe
at least 20 pairs of elytra, elytra
are on segments 2, 4, 5, then every other segment to 23, 26, 29, then
other segment to the end of the body. The edges of the elytra
are smooth (photo), and they
nearly meet along the
animal's dorsal midline. It has no prominent nuchal fold and
lateral prostomial antennae are inserted slightly ventral to the edge
the prostomium, may have few or sometimes no notosetae. The
are falcate, with pointed tips, and hooked. Most individuals
brick red, and the species has no dark band across segments 7 and
Up to 7 cm long.
Arctonoe pulchra (Johnson, 1897)
Common name(s): Red commensal
Polynoe pulchra, Acholoe
sp., Halosydna sp.
|Arctonoe pulchra, about 2 cm
long. Was living on the sea
californicus caught near Rosario.
|(Photo by: Dave Cowles,
How to Distinguish from
vittata has a band of dark pigment extending across
and 8. Arctonoe
has ruffled or folded margins on the elytra.
Range: Gulf of Alaska to Baja California,
Mexico; uncommon in California
Lower intertidal to 275 m
Symbiotic with several invertebrates
including sea stars such as Solaster
foliata, and Dermasterias
imbricata, sea cucumbers such as Parastichopus
californicus and P. parvimensis,
and other animals such
aspera, Megathura crenulata and
terebellid polychaetes such
as Loimia montagui.
is attracted by the smell of its host (if the host is uninjured), but
learn to live with a new species. Its body color is usually
to that of its host. It eats detritus. Adults are
and will try to drive other individuals off their host. They
injure or kill one another in fights over a host.
Members of Family
unlike most other errant polychaetes, have parapodia specialized for
rather than as paddles. Their longitudinal muscles, which
lateral undulations in other polychaetes, are poorly developed and they
don't undulate much. As a result, although they can walk
they are poor swimmers.
and Carlton, 1975
and O'Clair, 1998
et al., 1985
General Notes and
Observations: Locations, abundances,
The edges of the elytra on this species are smooth, as seen in this
closeup photo. This individual also has a red spot on each
Ricketts et al.
says all members of
the species have this spot (but that A. vittata do
not), while O'Clair
and O'Clair say that some individuals may not have the spot.
Authors and Editors of Page:
Dave Cowles (2006): Created original page