Abstract
The cirratulid polychaete Cirriformia spirabrancha
living in intertidal regions which are rich in
organic detritus has been studied. Results from
the studies on the feeding of this worm indicate
that C. spirabrancha is a selective feeder on
organic detritus, especially from algae that is
in the surface layers. Mucus production and
probable tentacle activity seem important in
food collection.
Cirriformia spirabrancha (Moore, 1904) occurs in
abundance in the intertidal regions of the Monterey Bay
beaches. These worms live primarily in noxious, black
mud or fine sand which contains high concentrations of
sulfates and organic matter. C. spirabrancha seem to abound
in areas where organic decay is high. Organic detritus
has been shown to be an important food source for many
inshore animals (Fox, 1950), and may be of similar im-
portance to this species.
Courtney (1958) reported that C. tentaculata in
England feeds mainly from the surface layers. George (1964)
gave evidence that this species is a non-selective substrate
feeder feeding on organic debris adsorbed to sand particles.
However, a much earlier investigation of C. tentaculata
(Flattely, 1916) suggested that this worm, unlike
Arenicola, does not simply live by passing sand through
its gut, but rather it selects nutritive organic particles
from the substrate. The quantitative analysis of sand and
feces, as well as microscopic observations, reported in
this paper indicate that C. spirabrancha feed selectively
from the substrate.
Supported in part by the Undergraduate Research
Participation Program of the National Science Foundation,
Grant GY-4369. I would like to thank Dr. John S. Pearse,
Dr. Welton L. Lee, and Dr. John H. Phillips for their
suggestions and guidance.
Materials and Methods:
Specimens of C. spirabrancha were collected every two
to three days during low tide in the mud-flats of the
Monterey Yacht Harbor and kept in tanks of running sea water
in the laboratory. Dissections of the gut of fresh worms
were done to determine gut content and whether the worm
actually ingested sand grains. Attempts at rate determinations
were also made by starving fresh worms in sea water without
any substrate for six hours and placing them in colored
sand or minute glass beads enriched with bacteria (which
was cultivated by leaving the glass beads in finger bowls
overnight with sea water and small amount of yeast extract
and glucose) for varying fifteen minute intervals. The worms
were then hand washed and placed in millipore filtered
(pore size of .45/) sea water until defecation occurred.
To establish the approximate level of feeding, containers
were set up with three layers of fine sand, the upper one
-3-
cm. of sand was dyed with toluylene blue, the layer one cm.
below with neutral red, and undyed sand was below two cm.;
the sand grains retained their dyed color and the dyes did
not seem to be deleterious to the worms. Ten worms were
placed in each container and allowed to burrow, the
containers then were placed in a tank filled with continually
running sea water. After 72 hours, the worms were hand
washed to remove the sand particles sticking to their bodies
and placed in filtered sea water. Phase microscopic
observations of the sand grains in the feces were carried
out after defecation.
The Walkley and Black wet oxidation method for organic
carbon content (Piper, 1944) was used for comparison of the
sand and feces. This method gives only a 75 percent
recovery for organic carbon content, so the experimental
results were multiplied by a factor of 1.3 to obtain the
actual (true) organic carbon content and then by the Trask
factor of 1.8 to obtain the total organic matter (Morgans, 1956).
Sand was collected from only the top 2-3 cm. from three
locations at the Yacht Harbor:
A- high intertidal
B- mid intertidal
C- always covered by water
Areas B and C were abundant with C. spirabrancha whereas
area A lacked them. The sand was washed well with distilled
water in a gooch crucible to remove salts and oven-dried
at 100-105° C. to constant weight. The sand was then passed
through a O.589 mm Tyler screen and approximately 2 gram
10
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samples were used in the determination. To collect the
feces, the worms were starved in sea water for 3-6 hours,
then placed in a substrate from one of the three areas and
left to feed overnight (14-20 hours) in a tank with
running sea water. Afterwards the worms were hand washed
and put overnight in filtered sea water in finger bowls
surrounded by running sea water with a temperature of about
15° C. The feces were collected from the water by
centrifugation and washed thoroughly with distilled water
and oven-dried to constant weight. Approximately 1 gram
samples were in the determinations. The same substrates
were used for each run and kept in a freezer when not being
used.
Results:
Dissections of fresh worms showed that the gut often
contained sand grains covered with mucus. Occasionally
sand particles as large as 1 mm in diameter were found. In
all the dissections the sand was found in the latter third
of the gut, even though the dissections were done from five
minutes after the worms were in the substrate and then at
hour intervals over a period of six hours; no visible
material was found in the anterior portions of the gut.
Worms that had been feeding in enriched glass beads displayed
the same phenomenon of one or two clumps of glass beads
with mucus in the hind gut. Jones (1968) also observed that
food material passes quite rapidly through the anterior
regions of the gut in the polychaete Magelona sp..
Ten worms were planted in the containers with layers
of colored sand for 72 hours. They defecated within 24 hours
after transfer to filtered sea water. The feces contained
both red and blue sand grains from the top two cm levels.
A few colorless sand grains from below two om also appeared
among the feces. These, however, might have been some of
the sand grains attached to the tentacles by mucus when the
worms were first placed in the dish. They could not be
removed without injurying the worm. The worms did burrow
in the white sand that formed the bottom layer of the
container, so there remains the possibility that the
worms do feed below two cm from the surface.
No precise feeding- turnover rates could be established.
Times from feeding until defecation varied from one to two
and a half hours. Part of the problem in determining
turnover rates, as shown by the gut dissections, involves
the indefinite length of time the worms hold food in the
posterior part of the gut. C. spirabrancha does not seem
to defecate only when feeding because it will defecate in
filtered sea water within twelve hours. During timed runs
for rate determinations the sampling dissections showed that
the worms were ingesting the substrate, but no correlation
between the length of time the worms were allowed to feed
and the time elasped before the feces appeared could be
found. Moreover, no actual ingestion of substrate could
be seen even though substrate particles were later found
in the hind gut. Since no definite time of feeding could
be established, rates were impossible to determine.
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The fecal pellets always contained large amounts of
mucus that enmeshed clumps of organic detritus and bacteria.
Organic analysis of the sand and feces indicated that there
was more organic matter in the feces than in the substrate
(Table I); the percentage of organic matter in the feces
varied widely, but all values were higher than those of
available organic matter in the substrate. The values
in the feces were high even when substrate A was used in
the feeding dishes. Substrate A may have been enriched
during feeding by the continual supply of fresh sea water
flowing into the tank where the finger bowls of substrate
and worms were kept during feeding time, providing the
extra organic material. Possibly bacteria grew on the
collected feces although precautions were taken to
keep the collecting containers covered, the temperature
between 13-15° C., and the defecating worms were placed
in millipore filtered sea water to remove bacteria and
organic debris.
In both the field and in the laboratory, the tentacles
were observed to hold onto small pieces of algae. In the
laboratory there was definite tentacle activity associated
with kelp; the tentacles responded immediately to floating
pieces (approximately two cm square) of kelp by wrapping
around them and holding them to the surface of the sand.
Usually only the tentacles were above the sand surface
while the rest of the worm's body remained buried one
to two om below the surface. Furthermore, often these
262
small pieces were slowly pulled into the sand until they
were completely buried.
Discussion:
The results from the feeding level experiments indicate
that C. spirabrancha feeds primarily in the upper two cm
of the substrate. The interface between the grey-white
surface substrate and the black sand-mud in which
C. spirabrancha lives is at about two to three cm;
C. spirabrancha probably feeds mainly in the grey-white
sand substrate. Courtney (1958) also suggested that the
species C. tentaculata feeds from the surface layers because
diatoms which live on the surface were in the gut and feces.
In addition, sea water contains much organic debris (Fox, 1950)
which deposits on the surface layers and adsorbs to the
substrate particles.
As Flattely (1916) suggested with C. tentaculata,
MacGinitie suggested that C. spirabrancha selects
nutritive materials rather than merely ingests substrate
particles indiscrimately. The high values of organic
content found in the feces compared to those found in the
substrate support this conclusion. Further substantiation
of the feeding selectivity is shown by the high content
of organic detritus and bacteria in the fecal pellets
with comparatively few sand grains; if C. spirabrancha
is a non-selective substrate feeder like Arenicola, more
sand grains would be expected in the feces. The mud-flats
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where C. spirabrancha lives are rich in decaying organic
material and are exposed daily to wave action which
proabably breaks down disintegrating organic materials
into minute particles.
The mucus covered fecal pellets and material in the
gut suggests that this worm feeds by mucous entrapment
of its food. The presence of many mucous cells in the
fore gut (Courtney, 1958) and the lack of teeth support
the idea of such a feeding mechanism. In fact, C. spirabrancha
seems to secrete mucus from its entire body and this
secretion of mucus could be a means for gathering organic
detritus. The polychaete Chaetoptus variopedatus has
been shown (Franklin, 1931) to feed in this manner, secreting
mucus and then ingesting the mucus and whatever material
has been entrapped in it. The mucus in the feces could
account for part of their high organic content, but the
worm must still produce more mucus to replace that which
is defecated; the need to produce moremmucus would require
a high intake of organic material. The rich organic
content of the feces together with the seeming aggregation
of this worm (Smith, 1968) points to the possible
importance of coprophagy as found in some other marine
animals (Frankenburg, 1967).
Tentacle activity around kelp suggests a possible
role of the tentacles in feeding. In his work on terebellid
polychaetes, Dales (1955) found that feeding was effected
by the tentacles bringing particles to the lips where
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sorting occurred. Jones (1968) noticed an immediate response
of the tentacles of Magelona sp. when a mass of detritus
was placed in contact with them. The tentacles of this
species made a loop, allowing the material to fall directly
to the mouth. Courtney (1958) remarked on the possibility
of food passing from the tentacular groove of C. tentaculata
to the mouth, although she never observed this phenomenon
directly. The vertical position of the long tentacles
in the environment makes the tentacles likely tools for
bringing food materials from the surface down near the
mouth region. In fact, MacGinitie (1935) reported that
C. spirabrancha feeds by extending its tentacles onto the
surface of the substrate to draw detritus into the opening
of the burrow where it is taken in by the mouth of the
animal. The present work further suggests that this worm
feeds on disintegrating organic material, and the tentacles
could play a major role in the feeding of this food material.
The holding of algae by the tentacles and the presence of
-carotene in the gut contents (found by the use of the
spectometer, J. Hult, personal comm.) strongly supports
the possibility that algae are especially important
as a food source.
References
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