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Diurnal and Tidal Rhythin the Oxygen Consumption
of the Gastropod, Tegula funebralis
Janna M. Snyder
Stanford University, Hopkins Marine Station,
Pacific Grove, California
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Janna M. Snyder
The purpose of this research was to determine if
Tegula funebralis (A. Adams, 1854) has a diurnal and /or
tidal cycle of oxygen consumption. The animals used were
collected at China Point, Monterey Penigsula, California.
The respiratory chamber was a 125ml vacuum flask
which was fitted with a small stopper in a large stopper
so that samples of water in which the animals had been
respiring could be withdrawn from the flasks with a small
tube fitted onto a syringe. This exposed a minimum surface
of the water to the atmosphere during the sampling.
An animal was placed in a flask along with a small
Terl was
Kled witt aeratel sa
magnetic stirring rod, sea water from an aerated cylinder
was run into a rubber tube attached to the side arm of the
let r te tr
flask, the flask was then sealedy and the animal was left
in the flask for a two hour period.
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Janna M. Snyder
Near the end of the two hour period, the contents of
by rden o
ede
the flask was stirred on a magnetic stirrer.This was to avoid
stratification of oxygen.eoneentratien wich might cause errors
in sampling. At the end of the two hour period two samples
were withdrawn from the flask and placed in 35ml Wker
bottles.
The Winkler method as described in C. Rogers (1929
was employed to test oxygen content.
After the samples had been taken a new aerated sea
water supply was provided for the animal for the next two
hours.
The first experiment employed five snails (one to
a flask) which were taken directly from the field and tested
for 25 hours. These animals were exposed to laboratory light
during the entire test period. Their oxygen consumption was
plotted against time and tide (Figure 1). From the pattern
obtained in this test, three more experiments were made to
These
check the trends observed in the 25 hour experiment.
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Janna M. Snyder
three experiments were run for shorter times occuring at
different tidal and diurnal periods. (Although values of
Grroxygen consumption per gram dry weight per hour tresptratton
were calculated, the trend can be shown as well in oxygen
consumption per two hours per snail. The histograms presented
gech
show the fluctuations of anindividual snail.
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When there were fluctuations between duplicates
Fan menn
Fagl
from the same flask, the highest value was used since the
(ertintnatien byai)
probability of an error showing greater consumption is much
less than that causing a low value eotawination by air).
Shoy
E-amining the histograms,esses that the
oxygen consumption of Tegula funebralis,although irregular,
seems to follow a tidal and diurnal cycle. Ie-one eempares
the-trends-at certafi-times and tidal peinteythe fellowing
can be-seent Although the values werghet always the highest
or lowest in the individual being examined, the trend is still
apparent. Figures 1,2a,3g show in 11 out of 11 times either
at high high tide or the periods immediately before or
Janna M. Snyder
immediately afterward, a trend toward lowered oxygen consumption.
At sunset or immediately before or after it, a lowered oxygen
consumption is evident in 11 out of 11 cases (Figures 1, 2a,3a).
During low low tide or the period immediately before or
immediately afterward, oxygen consumption increased in 11 out
of 11 cases (Figures 1,2a,4a). Oxygen consumption was increased
at sunsise over the values during the night in 7 out of 8
cases (Figures 1,la). Once again, it was either at sunrise
or the period immediately before or immediately afterward.
The respiration of small snails was generally greater
totek
than tre larger snails although a linear relationship does
not appear to exist.
Although the animals were collected at different
heights above sea level, and their condition of submersion
at the time of collection varied; the cyclic pattern appeared
to be basically the same. Some snails were treated differently
inside the laboratory: Three snails were sun in the dark
(May 15) along with the three snails which were tested in
Janna M. Snyder
laboratory light. The snails tested in darkness kept in
phase with each other except in one instance (Figure 25).
They displayed a reduction of respiration at sunset and
high high tide as did the snails in Figure 2a and were in
agreement with the normally tested snails at low low tide (skowin-
Thigher oxygen consumption).
Two snails, A and E, which had been tested on May 9
were kept in the laboratory for twelve days. They were exposed
to light during laboratory hours, submerged, but not fed.
differed from
Snail E disagreed-ieh its previous run in two places
(Figure 35). Its oxygen consumption was reduced at sunset.
It agreed perfectly with the rhythm of the snails on May 21
which were tested at the same time under the normal experimental
conditions. Snail A showed different trends in four places
out of six when compared with its behavior on "ay 9. It
disagreed in two places with the group depicted in Figure 3a.
The tides on May 9 and May 21 were similiar in times of
gdeg
earli
occurrence and sunrise was ten minutes later on May 21. If
Janna M. Snyder
the diurnal/tidal rhythm was not upset by this treatment, the
similiar times and tides should have given nearly perfect
agreement as in the case of Snail E. Since Snail E seemed
to follow the pattern and Snail A did not,itean netbe
not afparentt
oeneluded-that rhythm is destroyed by starvation or non-
exposure to tides.
Two of the snails tested in the dark on May 15
were kept submerged in the laboratory away from light and
food for ten days. When they were measured along with
normally run experimental animals on May 25, one was tested
in darkness and the other in laboratory light. They had the
oeriod
same trends except for one ihstanee (Figure la). When the
hours coincided (Figure 25), they agreed with their previous
trends three out of three times. Apparently rhythm is not
upset by darkness, absence of wave action, or starvation
over a ten day period.
CONCLUSIONS: The diurnal cycle of Tegula funebralis
is superimposed over the tidal cycle. The fact that the snails
consume more oxygen at low low tide and less at high high tide
Janna M. Snyder
suggests that an oxygen debt built up during high high tide
could be paid during low low tide when the snail has an abundant
supply of oxygen, areundhim. An eemet which might suggest
this is that in the field the snails come up out of the water
at night and on foggy days. It can be postulated that if the
snail is moist the respiratory exchange would be even better
in air than in water.

consulted Nr. Walter Holz 83) about investigating
oxygen debt during the two tidal priods. Tests were made
on three snails taken from submerged pools at high high tide
and three snails sitting on rocks in the air at low low tide.
The lactic acid content was approximately twice as great in
1. k.l the snals fron the nign higd tide s it was for tae mnalis
from the low low tide. Mr. Holz also noticed that a snail
which had been submerged in water of reduced oxygen content
would not come out of its shell and start respiring immediately
when it was thrown in fresh sea water. It would,however,
come out of its shell immediately when exposed to air.
anna M. Snyder
SUMMARY: The animals tested were allowed to respire
in sealed flasks and water samples were withdrawn every two
hours and examined for oxygen content by the Winkler method.
Investigation of Snails from China Point (Nonterey Penisula,
California) suggeste-that the snails have a lowered oxygen
consumption at sunset and high high tide, and an increased
oxygen consumption at sunrise and low low tide. The snails
may build up an oxygen debt during high high tide which is
repaid during exposure to air at low low tide. Lactic acid
content of snails at high high tide was about twice as great
as that of snails at low low tide.
Snyder
Figure Legends
Fig. 1. (May 9) 25 hour cycle. Absciasa: hours from sunrise; ordinates:
ml. of oxygen consu ed. Tide is in hours after sunrise;ordinates in feet.
SR, sunrise; arrow, sunset.
Fig. 2. (May 15) . a. short cudle (F,G.H.). EXXXXXXXXXXXXXXXXXXXXXXNXX
YXXXXXXXXXXXXMBMKXgXAXJKXXXBBXXXXXXXXXXKXXXBXXXXXXXXX). b. Dark tested
snails (1,2,3).
Fig. 3. (May 21). a, short cycle test (I,J,K); b, snails A and E from
May 9, styaved, submerggd,inlaboratory light for 12 days.
Fig. 4, (May 25). a, short cycle test (L,M,N); b, snails 1 and 2 from
May 15, submerggd and starved in dark for 10 days. 1, runin light;
2, run in dark.
C

Snyder
Literature Cited
Rogers, C. Gardner
1929. Laboratory Outlines in Comparative Physiology. McGraw-Hill
Book Co., Inc.;pp 1-130. New York, New York.
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