HORIZONTAL AND VERTICAL MOVEMENT
IN ADULTS OF THE POLYCHAETE ANNELI
CIRRIFORMIA SPIRABRANCHA
Philip E. Henderson
Hopkins Marine Station
Stanford University
Pacific Grove, California
Philip B. Henderson
Cirriformia spirabranche (Woore, 1904) is very common
along the California coast, inhabiting mainly sheltered
intertidal regions, although at times it extends to depths
in excess of 7 meters. During the spring of 1968, preliminary
examinations were made on various populations of intertidal
C. spirabrancha in the yacht harbor area of Monterey,
California. During these observations core samples taken
at the 0.0 ft. tidal level at both low and high tide showed
the presence of large numbers of animals when the sand was
wet, and an apparent complete absence of animals in the
same region at extreme low tide. This suggested possible
vertical or even horizontal movement during various stages
of the tidal cycle.
While work haskbeen carried routdonusome aspectspect
of the biology of cirratulids by George (1964), Flatterley
(1916), and Courtney (1958), there have been no investigations
concerning the movement of the adult animals. Because of
this general lack of knowledge concerning the movement of
adult polychaetes and because initial field observations
on C. spirabrancha suggested rather extensive movements of
the adults of this species, an investigation was initiated
to determine the presence, magnitude and characteristics
of movement of the adults of C. spirabrancha
Philip E. Henderson
MATERIALS AND METHODS
Field experiments were conducted in the yacht harbor
area of Monterey, California, during the spring of 1968.
The directional movement of adult C. spirabrancha in a
population at about the 0.0 ft. tidal level was investigated
in the following three experiments.
To test for horizontal and diagonal movement two
1xlx0.33 ft. wood-framed containers, screened on the top
and open at the bottom, and two O.5x0.5x0.33 ft. wood-framed
boxes were used (figure 1). A one cubic-foot hole was dug
during a very low tide. The large box was placed in the hole
with its screen facing downward. One of the smaller boxes
was placed at its center. Sand extracted from the hole was
sifted into the opening to remove any adult Cirriformia
which might have been present. When the sifted sand was level
with the surface, a smaller box was placed at the center and
forced into the sifted sand. The remaining large frame, screen
facing upward, was forced down until the screen touched the
sand. Screens allowing for the passage of water were
specifically placed to prohibit the worms from entering from
above or below, yet still allowing them to enter from the
sides. The substrate between the two smaller boxes was examined
every third day for a total period of twelve days.
To test possible movement through the surf, a 0.125
cubic-foot container with wooden sides, screened bottom, and
open top, was buried during a very low tide, its top flush
with the substrate surface (figure 2). To prevent worms from
entering over the lip, a flanged screen collar was extended
Philip E. Henderson
from the lip 3 in. outward to cover the surrounding sand.
The box was filled with sifted sand taken from the area.
The sand in the container was examined 4 times during a
12-day period.
To test the range of vertical movement, a 4x20 in.
polyethylene cylinder, filled with sifted sand and capped
on the top, was buried during a very low tide. The cylinder
was removed at high tide and the contents examined for the
presence of the polychaetes. This experiment was repeated
times over a 12-day period.
Preliminary studies indicated that tentacles of some
individuals were present on the substrate surface throughout
the tidal cycle except when the sand surface was above the
water level and dry. Movement patterns of the population
were charted by placing dyed animals in given areas and
observing their dyed tentacles on the surface of the substrate.
Neutral red, Bismark brown, and Toluylene blue were found to
be the most effective dyes after tests in which the organisms
were submerged for 2 hrs. in a solution containing 1 liter
of sea water to 2 gms. of dye.
500 worms were placed at various stations in the field
area. The number of worms was measured volumetrically since
excessive handling was found to be fatal. Approximately 500
worms can occupy a volume of 300 ml., hence 300 ml. containers
filled with dyed animals were estimated as containing 500
animals.
Four stations were chosen on the basis of their
variability in three pertinent conditions: density of the
Philip E. Henderson
existing population, sand particle size, and tidal level.
Station A was at a depth of -2.5 ft. The substrate
was very fine, with 7%% of the sand having a diameter of
less than 0.124 mm. (as determined by dry weight). The
interphase between aerobic and anaerobic substrates (white
vs. black sand) was 4 cm. below the surface. The population
density was found to be 3,200 worms/m as determined by
random cores.
Station B was situated at 10.7 ft. The sand here also
was fine, with 76% of it having a diameter less than
0.124 mm. The interphase was 5 cm. deep. The worm population
density was 2,700/m. Periodically, mild turbulence resulted
from tidal changes.
Station C was situated at 40.3 ft. The sand size
was much coarser here with 19% of the sand larger than
1.397 mm. in diameter and 45% smaller than 0.124 mm. in
diameter. The area was surrounded by large boulders, which
might possibly hinder horizontal movement of the worms.
The population density was 750 worms/m.
Station D was situated at +0.1 ft. It was centered
on a broad, sandy plain, where tidal changes created much
turbulence. The particle size of the sand was coarse, with
24% larger than 1.397 mm. in diameter and only 29% smaller
than O.124 mm. in diameter. Population density was 1,900
worms/m?.
Neutral red-dyed worms were placed 3 in. deep in a
in. diameter hole (the "origin") att each of the stations. For five
Philip E. Henderson
days, these areas were observed at the 4 extremes of the
tidal cycle. The number of tentacles and the movement of
the tagged individuals were recorded. Each station was
observed for an additional two days only at high tide. On
the 8th day, a 2 ft. diameter hole was excavated at each of
these "origins" to determine the number remaining.
The experiment was repeated using worms dyed in Bismark
brown. The tagged worms were observed during the extremes
of the tidal cycle for two days and during high tide for
two additional days. The test was again repeated using
Toluylene blue to dye the tentacles. The animals were observed
at high tide for 6 consecutive days. Afterwards, the sand in
a two foot diameter circle around the origin was sifted and
the number of dyed individuals recorded.
It is extremely difficult to determine the number of
tagged individuals present near the surface. Each Cirriformia
extends an estimated 5 to 10 tentacles above the substrate.
When a population was scasparse, it was assumed that all
tentacles projecting from the same point belonged to a single
worm. Based on the assumption that each worm put 7 tentacles
above the surface, a visual estimate was made of the worms
present in a dense population.
Tentacles on the surface do not necessarily indicate the
density of the population present under the surface of the
sand. Consequently, cores were taken at stations B, C,
and D during the four extremes of the tidal cycle to determine
whether there was a constant ratio of tentacles on the
r
surface to the worm population density underneath. Tentacle
Philip E. Hendersor
numbers were recorded in a 4 in. diameter circle and a 10
in, deep core was taken. Since the density of tentacles on
the surface is variable, efforts were made to include both
"heavily" and "lightly" populated areas as estimated by the
number of tentacles apparent on the surface.
Meanwhile, an attempt was made to determine whether the
same relationships occurred in samples taken during a night-
day cycle. Four containers 1 ft. and 5 in. deep were placed
in an outdoor tank. The containers were filled with sifted
substrate and with 30, 150, 250, and 500 worms respectively.
Water height was kept at a constant level of 1 ft. above the
sand surface. The ratio of tentacles to the total population
was recorded day and night for 4 days.
RESULTS AND DISCUSSION
Cirriformia appear to move diagonally and possibly
horizontally. The submerged cylinder testing the possibility
that animals migrate vertically below twenty in. failed to
detect migration from these depths (table 1). If any worms
had descended below twenty inches during low tide, they should
have returned again toethe surface at high tide when tentacles
of Cirriformia reappeared in the adjacent area. Observations
that neither Cirriformia nor their mucus tubes were present
below eight in. (Smith, 1968) likewise confirmed this.
Movement through the surf cannot be an important means
of transportation; not even an occasional worm appeared in the
container which allowed only surface moving organisms to
enter, except that in one instance two worms were found in
Philip E. Henderso
the apparatus. Heavy surf, however, had buried the container
under three in. of sand, possibly allowing entrance through
the substrate (table 1).
The container allowing horizontal and diagonal migration
did contain many worms after three days. If the worms entered
horizontally from the surrounding substrate, they should have
dispersed randomly throughout the container. In fact,
Notomastus, an errant polychaete commonly found in the same
substrate as Cirriformia, was evenly dispersed throughout
the container. If movement were diagonal, however, worms
could reach the center box only by a zig-zag pattern of
burrowing-- moving upward diagonally, retreating along a
different path, and then coming up again in a different
direction. Few worms would therefore be expected in that
case to reach the inner box. Indeed, a disproportionate
number of Cirriformia were found in the area between the
small boxes. Only an average of ten percent of the worms in
the entire container were in the middle section which occupied
thirty percent of the total volume.
Tentacle counts indicated that at all times only
approximately forty-five percent of the animals had their
tentacles showing above the surface of the sand, except when
the sand was uncovered by water, in which case all the
tentacles were retracted (table 2).
There was no regular migratory pattern noticedlduring
experiments in which the movement of dyed worms were observed.
The dyed worms were dispersed equally in all directions from
the four "origins" (table 2). The rate of movement was
-9-
Philip E. Henderson
slow, after sig days a few individuals had moved as far as
five feet, but an average of eighty percent of the worms
were still clustered about the "origin" (figures 3 and 4).
Unfortunately, the staining process seems to have had
lethal effects on the organisms. When the "origins" were
excavated at the termination of an experiment, no more than
half of the worms originally planted could be accounted for
and decaying Cirriformia pieces were observed on two occasions.
During other experiments, several stained worms were seen
protruding from the substrate with decomposing skin. Yet
many stained worms lived for over one month with no apparent
side effects.
The unexplained disappearance of Cirriformia which
initially led to this study could perhaps be accounted for
by the aggregation tendencies of the worm. Concurrent
experiments (Smith, 1968) indicate that the worms often
are found in densities greater than 750/100 cm in 1 to 15
foot diameter clumps, 1 to 5 feet apart. Practically no worms
were found between such clumps. The initial coring may by
chance have included only unpopulated areas during low tide
and only aggregated areas during high tide.
Results of these experiments, then, indicate little
movement of adult Cirriformia. The movement that does occur
appears to be small and random. These results suggest that
populations of adult C. spirabrancha are relatively stable
and tend not to move once established.
Philip E. Henderson
SUMMAR
Movement of Cirriformia is random and not extensive.
2. Cirriformia appear to move diagonally, and possibly
horizontally
3. The number of tentacles observed on the surface of the
substrate in a given population seems to represent only
35 -55% of the total population during night and day, and
during all phases of the tidal cycle except in dry sand during
an extremely low tide when their tentacles are retracted.
4. Evidence indicates Cirriformia remain in the upper 8 inches
of the substrate.
ACKNOWLEDGEMENTS
This work was supported ta part by the Undergraduate
Research Participation Program of the National Science
Foundation Grant GY-4369. My sincerest thanks are given
to the faculty and staff of Hopkins Marine Station of Stanford
University for allowing me to do this study, and especially
to Dr. Welton Lee for his suggestions and guidance in the
execution of this paper. I am also gratefully indebted to
Mr. Roger Szal for his encouragement and assistance.
C
Philip E. Henderson
REFERENCE!
Courtney, W.A.M. 1958 Certain aspects of the biology of the
cirratulid polychaetes. Ph.D. Thesis. Univ. of London.
Flatterley, F.W. 1916. Notes on the ecology of Cirratulus
(audouinia) tentaculata (Montagu). J. Mar. Biol. Ass.
U.K., 11: 60-70.
George, J.D. 1964. One some evnironmental factors affecting
the distribution of Cirriformia tentaculata at Hamble.
J. Mar. Bio. Ass. U.K. 44: 383-388.
Smith, D.A. 1968. Personal communication.
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ermanent Address
FOOTNOTES
C
Tabl
Number of C. spirabrancha found in apparatus testing
horizontal and diagonal movement through the substrate (A),
vertical movement below 20 in. (B), and movement through
the surf. (C).
Tria
between
inner boxes
2. between
63
outer boxes
Table 2
Dispersion pattern of Cirriformia. On 6 consecutive days, the
number of worms in each quadrant surrounding the "origin" were
counted. The table shows the mean percentage and standard
deviation as a percentage in each quadrant.
Quadrant
III
Station A
289
20%
Mean
26%
26%
5%
8%
Standard Deviation
5%
Station B
25%
Mean
27%
16%
4%
Standard Deviation
6%
Station C
26%
25%
Mean
259
24
5%
7%
6%
Standard Deviation
Station
25%
29%
26%
Mean
4%
3%
Standard Deviation
Philip E. Henderson
Table ?
Ratio of the number of Cirriformia showing tentacles on the
surface to total population in the same area. Counts were
made during two nights and days in the laboratory under
conditions of constant water height. The remaining counts
were made in the field for three days at 3 tidal extremes.
erio
No. of samples
Mean ratio
Standard Deviation
Nigh
.45
Day
.46
High Tide
.49
Lower High Tide
.43
.11
Higher Low Tide
.45
TABLE 4
Number of dyed worms in substrate within 1 ft. radius of the
'origin" the day after completion of the experiment. It was
impossible to obtain data from Station A. Initially, 500
worms were present at each station.
Experiment I Experiment II Experimer
Station B
15.
236
Station C
21.
33.
Station
FIGURE LEGENDS
igure 1. Apparatus testing diagonal and horizontal movement
of Cirriformia through the substrate.
Figure 2. Apparatus testing possible movement of Cirriformia
through the surf.
Figure 3. Distance and number of dyed tentacles observed away
from the origins 6 days after the third experiment. The
organisms within one foot were not included since the majority
were in an aggregation within that åreasneEach number"on the
abscissa represents the distance from the "origin." The points
on the graph represent the total number of dyed animals
observed between the corresponding distance from the "origin"
and the next recorded distance.
Figure 4. Total number of dyed worms at and near the "origins,"
seen during a series of high tides for 6 consecutive days after
implantation. The results are indicative of those obtained in
two additional experiments.
20
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