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Preliminary notes on the growth rates of Tegula funebralis and
of Acmaea asmi
I. Installation of cages:
The majority of the time this quarter was spent on this
phase of our project. The installation of the cages proved
to be a more difficult task than was originally intended
and consequently took more time. Our initial populations of
both species were able to escape within two weeks, but the holes
in the cageshave since been closed. We now feel that
we have an adequate means of confining the animals, one which
will withstand the environment and one which does not
adversely affedtthe population; i.e. five T. funebralis
died over a period of three months. However each was found
stuck between the cage fittings and the ground, and we
felt that their death was caused by being caught in an
attempt to escape and not, therefore, having access to
food, etc.
II. Marking
Our original marking system proved to be unsatisfactory
due to erosion of the shell apex; subsequently we marked
T. funebralis on the sides of the shell. A. asmi's markings
proved adequate. Our process is as follows: 1) applying
a base coat of red nail polish; 2) writing a number on this
base with Indian ink; 3) Covering with one or two coats
of clear polish; 4) renewing the numbers and top coat
at least once a month.
In addition, we plan to try etching numbers into the
shells next quarter and cutting the lip of the T. funebralis
III. Measurement:
Due to additional time spent on the above preliminary steps
adequate measurement of growth was not completed. The method
used was to measure the largest basal diameter of the shells;
however, the results were poor as for over two hundred
T. funebralis marked, of which we have subsequent
196
O
measurements of twenty-five, only five increased their size
measureably, each by .5 mm and, having measured these animals
many times, it has been concluded that .5 mm is our error range.
Not a single a. asmi grew a measureable amount although we
measured both widest basal diameter and length from base to
apex along the widest curve.
The loss of population made it extremely hard to view a
large sample size over the entire quarter. As stated above,
we plan to scratch T. funebralis' lips amd to measure the
distance traveled by the mark. In this manner a more predise
measurement will be obtained. As for A. asmi, we're still
thinking of a manner to obtain precise measurements and
have not been successful.
C
Dec. 12, 1963
Dear Dr. Abbott,
Both Willie and I apologize for not having sent you some
preliminary data sooner. However, after we last saw you,
time has been so scarce (Thanksgiving, finals, etd.) that
this is the first change we've had to sit down tomarize
our work this quarter.
Although our results are preliminary if that, hopefully
the following will give you a better idea of what we've
spent the past quarter working on.
Also... have an enjoyable and profitable trip next
quarter, and a Merry Christmas to you and your family.
Sincerely,
Wille
Dars
gde g 2 Coreng
en) gren 16 de 1e
D0
191
Studies of
Aomaea asn




ne
am ai
11
Diane Wickiz
zl
Acmaea asmi
eptenber
rom
ula funebralis and o
opulations of
were measur
bi-we
Acmaea asmi
and the
e
to determine their growth rate
growthr
ations, if any, of these rates.
ach animal was follõwed individual
in the
animals remained, so far as possi
nvironment.
summary
lowi
pre
sections:
divided into three
per
construetio
which included design,
work
methods of marking
cages;
ad installation of
and considerations
giver
the animals
and measuring
data and conclusions.
eedure; and (3)
the cages were
to be made witt
less steel wire mesh, but after consultation
deoided that for
wire manufacturers,
mited period of a year, galvanized
We
the
hen galvanized
tand
der
the
latig
thod
thodinstead
roide a structure most resistan
diameter
refers
rosion.
Nunbet
ins
el mesh was selected in order
vet
ter through the cages and
4. asmi within them.
a
place the animals on a n
ges were placed on flat rock
shady crevices and lush algae
solid rock
drilled holes
bolts into the
and
inho
galvanize
bottom of the cages
t.
the
cal
the cages was based on eco.
The cag
practical considerations.
funebrali
had been
reas
where
placed
in
Wright, 1963) and in one cas
see War
and
erved
and the largest percent
funebrali:
4. asmi had been found.
the summe
sages were made during
that
eptember
eed in position in
sec0
in position, the
the oages we
ect, that of marking and
We attempt
could be started.
ay as t
the ani
erence with growth.
painted a smal
funebralis
the
shell with
finger-nai
Laced an india-ink number
on the polish
painted'a protective outer coating
clea
te markings were placed on the top of the shelle
asmi
asmi are infrequently found.
The
here
in the same manner. The marking
e mark
funebralis
unt
te was continued on
the
1964; the marks had remained legible
ebruary
a maximum of three weeks during earl
fall a
esseerds as the sur inereased during
season. After February, we used a small
number
original
0 imprint each animals
hel
..
method; i.e.equals 2,..
quals
his method could not be used for the
their shells are extremel
penetrated the shell, killing
the nai!
olis markings remaine
smt for
the
wooth
ani
e taken
for e
dual
urements we
indi
we measured the large
weeks.
Originally,
using this as
ameter of the
an inde
shell
al
nebra
both
28
T.
207
erpendicular distane
In Februar,
ted
A. asmi was al
each
fune
ile mark was placed on each
distanc
the
wing lip;
of the
the ede
the mark was not
on
progressed
hat
the
inde
growth
us a second
thus giving
wekki
measurements were made using a standard
ernier calipers calibrated in nillimeter.
method of measuring growth was cõnsidered:
hi
rowing lip as a zero point
use the mark at the
then to measure the degrees of growth rotation
and
racter placed at the apek of
the
The error inherent in this method proy
both because of the irregularities
ac
of the
shells and of the
estimateduthe error iaherent in ur
funebral
individually marked
ift.
ements.
for each of five measurements
selected randomly
rgest basal diameter of the animals varied b

didn't grow
nebralis
3 cm. Because
the
enough, we were unable to calculate a measure-
However
for the lipgfrowth technique.
aliminated the error due to
20
the calipers, the total erwor would probably be
approximätely the same because the caliper's themselves
e.

are accurate with certainty to only .1 cm.
temet
Cage number one was placed in an area of pounding
(area 4 3 as laid out by Wära and Wright, 1963).
surf
hot
groups of 100 T. funebralis and
For four months,
mi, all individually marked, were placed in
two weeks. At each of the eight
the cage every
they were found completely crushed
measuring
periods,
by broken shell fragments which had been pounded into
Since only dead- animals and shell fragments
the cages.
no measurements were made. The cage was
were found,
positioned on top of a large flat rock which had what
seemed to be an adequate number of crevices. However,
cages obviously limited the animals' movement
the
into more protected areas and resulted in their being
battered to death by shells. At the end of four months,
cage number one was abandonned.
Cage number two was placed in a more secluded
and Wright, 1963) and was
area (area + 5, Wara

protected by numerous wharf pilings and rock formations.
sand twenty-fiee A.
One hundred T. funeb
asmi,
in this cage
all individually marked, were maintained
21
If the animals
throughout the experimental period.
or were lost, they were immediately replaced.
died
funebralis ranging in size
from .5 cm. to
and 4. asmi
5 cm. mesu
tbasal
diamete
of the shell, we
mar
attempted to maintain a normal distribut
opularion in order to determine whet
different sized animals grew at different rates
case, for either T. funebralis o.
A. asmi
ablt to note growth which exceeded our ex
erimental error.
Although only eight T.
unebra
ind three A. asmi remained and were measured for
entire nine month
funebralis and
ter
Je months
kept for a period
smi
January



Assuming that
approx.
T. funebleis
he same size grow at the Same rate.
replael
imals should not negate the validity
oui
hus, if growth measurable by our me
ng
in the population at large,
b
record it.
of our datalis negative
use
that we have not been able to record
grow
measurements are
included in this
paper
hree possible reasons exist that might explai
lo groth was neted for
either aninal.
Hre

oth
T. funebr.
s and A.
grow slowly
as
ndicate that survivors of both group
have
life spans.
one must
Second,
alize
only nine mont
asurements
were made during
ear.
possible that
and
bot
funebrali
summer months and
ismi grow
durir
the
idly
ne months.
ttempted to retain the ecolo
fünebralis
that neither
onment it is possible



Although the
the
cages
vere
hap
281
overing,
lush algae rock
had access
mals
an
element
lietary
hat some
ossible
the
limiting factor
this was tne
bottom
free movement. fron
adequate water circulation, possi
the
ave further limited
the cages, could

1 should be nõted that thegrowth rate

was not noted; one eõuld as
small animals
rapid.
rmore
these would be
hat
an attempt was made to determi
summar
funebral
4. asmi and of
rates of
in a natural environm
mäintained
ulatins wee
nine months and all animals were individual
technique
a ser
measured, using
arked and
ry two weeks. No growth was n