EFFECTS OF MATER HEIGHT, TEMIELATORE, AND LIGHT
INTLNSITY ON THE MOVEMENTS OF THE FOLYCHAETE
CIRAIFOLMIA SIIRABLANCUA (MOOKE, 1904) (1.)
sortins larine Station.
Facifie Grove, California
(
ABSTRACT
The effects of water height, temperature, and light intensity
on the movements of the marine annelid Cirriformia spirabrancha
were investigated. Of these three environmental factors, only
changes in water height elicited movement in C. spirabrancha
in that the worms only reacted to an absense of water on their
tentacles and body.
Irubcrin
Cirriformia spirabrancha is a marine annelid found in both
the intertidal and the subtidal sulfide rich mud of the Pacific
coast. Intertidal populations, at least, are subjected to
many environmental fluctuations, especially fluctuations in
water height, temperature, light intensity, surf action, and
oxygen tension. Many organisms exhibit cyclic behavioral pat-
terns which are in fact based upon some of these types of fluc-
tuations (Fingerman, 1960). However, nothing is really known
concerning the behavior of C. spirabrancha (MacGinitie, 1935),
or of other related species (George, 1964). Because of this
lack of knowledge on the behavior of cirratulids and the possi-
bility that some of this organism's behavior might be related to
the effects of water height, temperature, or light intensity,
a study of the effects of these parameters on the behavior of
C. spirabrancha was made. The results indicate that only one of
these three factors, water height, effects the behavior in this
species.
MAIERLALS AND METHODS
The experimental worms were obtained from the top 10 cm of mud,
at approximately the plus 1.0 foot tidal level, in the Monterey
yaught harbor. Two glass tanks (one 30 cm in width, 50 cm in
length, 40 cm in height; the other 30 cm in width, 70 cm in length,
60 cm in height) were used in the laboratory experiments. These
were set up in the following manner. Each tank was filled to a
height of 30 cm with sand from the worm's natural environment.
In each tank a glass plate was inserted in the sand along one
of the glass sides of the tank, about three fourths of a centi-
meter from this glass side, in order to facilitate observations
Initially both tanks were filled with running sea water main-
tained at 12.5° C. This temperature was maintained by the use
in each tank of a Heyco probe heater and a Chemical Rubber
Company thermometer, connected through a minitrol relay box
outside the tank. Each tank was equiped with an airator, which
was kept running at all times in order to assure adequate
oxygenation of the sea water. Both tanks were placed under a
variable light source capable of a maximum illumination, at the
waters surface, of 1,500 foot candles. Initially the light
intensity was maintained arbitrarily at a constant 750 foot
candles. During the experiment on varying light intensities,
a Holiday appliance timer was connected to the light source in
order to control automatically the hours of light and darkness.
RESULTS
LEPECTS OE ILMLENATORE ON TIE MOVLMENIS OE C. SILABrANC
In order to test the effects of temperature on the behavior
of C. spirabrancha, worms were added to the smaller tank and
allowed to burrow. During the four days in which the worms
were allowed to settle and burrow, the water in the tank was
maintained at 12.5° C. Throughout the experiment, the light
was kept at an intensity of 750 foot candles, and the water
height at a constant 10 cm above the sand surface. In a small
section of the tank where the worms could be observed, the number
of tentacles visible above the sand were counted and the lengths
of these tentacles recorded (lengths estimated at 0.5 cm, 1.0 cm,
or 1.5 cm). Likewise the body depth of each of the worms
visible against the glass was recorded. The temperature was
then changed - one degree per half hour - to 11.5° C, and held
at this temperature for six hours. After this period, the
temperature was again changed in a similar manner to 18 ° c,
and held for six hours. Finally the temperature was changed once
again in the same manner to 22 0.C and held there for a final
six hours. At one hour time intervals throughout the entire
experiment the number and length of tentacles, as well as the
body depth, were recorded. This experiment was repeated twice
using different groups of worms each time. No change in tentacle
number or length, or in body depth in the sand, was observed
with these changes in temperature. An additional series of
experiments were carried out in which the temperature in the tank
was first taken up - one degree per half hour - from 12.5 0 C
to 22 ° C, then lowered in the same fashion to 11.5° C. Again,
after three trials, no change in tentacle number or length, or
body depth, occurred.
EPFECIS OF LIGHT INILNSIIL ON LAE MOVLMLNIS OF C. SELRABLANCHA
Worms were added to both tanks and alloved to burrow in the
same manner asiin the previous experiment. Throughout this
experiment, the temperature was maintained at 12.5° C, and the
water height held at 10 cm above the sand in the small tank
and 30 cm above the sand in the large tank. The timer was wired
to the light source in order to automatically provide a con-
tinual day-night cycle (a 12 hour day of constant illumination
of 1,500 foot candles and a 12 hour "night" at a constant
intensity of under 25 foot candles). The worms were observed
every hour for two days. The tentacle number and length and
body depth were found not to change significantly under this
light regime. Following this experiment, one tank was kept
under a constant illumination of 1,500 foot candles, and the
other tank at an intensity of under 25 foot candles. Both tanks
were maintained for 24 hours, and observations made every hour.
Again no differences in movement were observed in the animals
in the two tanks.
LERECTS CE VATEA LEICHI UN LIL MOVLaLNIS Or C. SElAAEANCHA
Norms were added to the large tank and allowed to burrow in
the same manner asin previous experiments. The temperature
was constantly maintained at 12.5 ° C, and the light intensity
at an illumination of 750 foot candles. Although fresh sea
water was continually being pumped into the tank, the water
level was lowered at a rate of 8 cm per hour by means of a siphon
with a flow rate slightly faster than the rate of the inflowing
sea water. The water level was raised again by breaking the
siphon action and allowing the normal inflow to fill the tank.
The sea water was lowered from 30 cm above the sand to 10 cm
below the sand surface and then raised to 30 cm above the sand
again. The observations from ten such trials showed that while
the water level was lowered from 30 cm above the sand to 0.5 cm
above the sand, the tentacle number and length above the sand,
and the worm (body) depth in the substrate, remained unchanged.
As the water level dropped from 0.5 cm above the substrate to
the substrate surface, about half of the tentacles were with-
drawn from the surface and were seen to lay next to the body
of the worm. The other half of the tentacles decreased in length
above the sand and lay in the moisture of the thin water film
which had developed on the sand surface. When the water level
in the sand reached the head of the worm, the worm would contract
and move, tail first, down its mucus tube. It continued to
burrow downward, tail first, until it was immersed in the water
again. When the water level was again raised, the worms either
came up to theesurface again in their old mucus tubes, or
burrowed upward along a new path, forming new mucus tubes as
they burrowed.
CCORDINATED FIELD OBSLNVAIIONS
Two field areas in the Monterey yaught harbor - one at the
plus 1.0 foot tidal level, the other at the minus 1.0 foot tidal
level - were observed at one hour intervals over several 24 hour
periods. The temperatures observed varied from 12° C to 22.5 C,
the water heights during these observations varied from two
meters above the sand to 4 cm below the sand surface, and the
light intensities immediately over the worms varied from less
than five foot candles to over 3,000 foot candles. The tentacle
number and length above the sand were recorded. The results
indicate that only the absense of water over the tentacles causes
them to be withdrawn into the sand, irregardless of the light
intensity and temperature.
DISCUSSION.
Some annelids, notably Hirudo and Glossiphonia, are attracted
by certain temperatures (Dales, 1963). Temperatures of 11.50
to 22° C, the temperatures found in the natural environment
from which my experimental worms were taken, do not effect
movement in the worm C. spirabrancha. Some isolated colonies
of worms may be subjected at times to temperatures greater than
22 ° C, but these temperature extremes were not tested.
Earthworms show a negative phototaxis when subjected to light
of high intensities, but negative phototaxis when subjected to
light of low intensities (Dales, 1963). Cirriformia spirabrancha
were tested in the laboratory at intensities from 25 foot
candles to 1,500 foot candles. An intensity of 25 foot candles
was used for the "night" studies, instead of O foot candles,
in order to facilitate observation without, introducing another
light at the time of observation. An intensity of 1,500 foot
candles was used for the day studies, as it was the maximum
intensity available under laboratory conditions. These intensities
effected no movement of g. spirabrancha. Field studies were
carried out to see if lower and higher intensities would effect
movement. These natural intensities, O foot candles to over
3,000 foot candles, did not seem to effect any movement.
Water height effected movement in C. spirabrancha in that
the worms only reacted to an absense of water on their tentacles
and body. The laboratory and field results seem to indicate
that the tentacle number and length above the sand, and the body
depth in the sand, remain constant if the water level is 0.5 cm
above the sand or higher.
OOROIES
(1.) This investigation was supported in part by the Under-
graduate Research Participation Program of the National Science
Foundation. Grant GY-4369.
(2.) Present address: Stanford University, Falo Alto, California.
28
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