As a member of
family Arenicolidae, this species is large and wormlike, without
eyes, has few if any external head appendages but does have a prostomium.
It can evert
during feeding, which appears as a wide mushroom-cap-like structure (photo).
Most segments are not longer than wide. Many of the parapodia
but the body
is not covered with special paleae,
felt, or elytra.
setae (eg notosetae)
are not cross-barred. Segments in the middle third of the
have gills (see above photo). Features distinguishing this
include the fact that it is a large worm (over 2.5 cm as an adult)
does not secrete a tube, the posterior third of its body has no setae (photo),
its gills are bushy (photo),
4-7 pairs of esophageal caeca, the first of which is the longest, the neuropodia
of its posterior gill-bearing segments do not nearly meet at the
and its nephridiopores
are completely exposed. Thirteen or less gills.
Length to 15
cm. The anterior, middle, and posterior body portions often
slightly differently leading to the "neapolitan" designation.
pacifica Healy and
Common name(s): Pacific lugworm, Pacific neapolitan lugworm
on March Point, Padilla Bay, June 2009. View is of the dorsal
right sides. Anterior end is to the right. The red,
are gills filled with blood which has red hemoglobin. In
one can see that the gills are continually flexed and turned, providing
water flow over them.
|(Photo by: Dave
How to Distinguish from
marina has the neuropodia
of its posterior gill-bearing segments nearly meeting at the midventral
has the ventral side of its nephridiopores
covered with a flap of skin and it lives in areas with more wave
Many lugworms (family Arenicolidae) can be fully reliably distinguished
only by internal anatomy.
Japan, Pacific coast
from Alaska south to Humboldt Bay in northern California
Intertidal and subtidal;
Muddy sand of quiet, non-exposed
Lives in an L-shaped burrow, head down. It everts its
pulls it in, thus ingesting mud and feeding on organisms such as
within it. Periodically it backs up to near the surface to
forming the characteristic mound around its burrow. The mound
often have coils of castings roughly 1/2 cm in diameter. The
pulses its body while within the burrow to bring in oxygenated water.
and Hanby, 2005
et al., 1985
General Notes and
abundances, unusual behaviors:
This ventral view of the head shows that it has no obvious external
This view, taken a few seconds after the one above, shows the large
esophagus which is everted
during feeding. The esophagus expands outward like the head
The anterior third of the body, anterior to the gills, has
long segments and the notopodia
well separated. In this view the head is to the right and
is up. The first gill-bearing segment is on the
left. The capillarynotosetae-bearing
can be seen near the top of the segment in the center, while the uncini-bearing
can be seen well below the notopodium
next to the piece of debris.
The gills are notopodial
(dorsal) and filled with hemoglobin-containing blood. The
writhes and waves them gently, likely increasing water circulation over
them. Note the long capillary
setae on the notopodia
(top) and the uncini
on the neuropodia
The posterior segments have no setae, so that the back third of the
body appears almost like a "tail". Note the last gill and setae-bearing
segments at the right of the photo.
This is a view of the last segments and the pygidium (posteriormost
This ventral view of the posteriormost gill-bearing segments shows
that the neuropodia
of these segments do not nearly meet at the midline.
The worm creates burrows with large mounds at the entrance such as
this one. Often fecal castings can be seen on top of the
Authors and Editors of Page:
Dave Cowles (2008): Created original page
CSS coding for page developed by Jonathan Cowles (2007)