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Weights and linear measurements of the body and organs of the tiger salamander before and after metamorphosis compared with the adult.

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Weights and Linear Measurements of the Body and
Organs of the Tiger Salamander, Before and After
Metamorphosis, Compared with the Adult
HOMER B. LATIMER AND PAUL GIBBONS ROOFE
Department of Anatomy, University of Kansas, Lawrence
ABSTRACT
Body weight and length, weights of 14 organs and 15 linear measurements are presented from 97 Amblystorna tigrinurn melanosticum before metamorphosis and 57 specimens after metamorphosis. These data are compared with similar
measurements (previously published) on adult salamanders.
Body weight and weights of the digestive tube and its subdivisions, liver, pancreas, spleen, eyeballs and brain are heavier in the larvae. The body weight decreases
more than many of the organs and hence the percentage weights of the heart, lungs,
liver, spleen, kidneys, gonads, eyeballs and brain are larger, relatively, in the postmetamorphosis salamanders.
Since body length is not significantly changed, the percentage lengths are much
the same. Length of the digestive tube and its parts, jaw width and the width of the
body a t pectoral, belly and pelvic regions are all longer in the larvae. The limbs are
the only percentage lengths greater in the post-metamorphosis salamanders.
All of the weights and all of the linear measurements are significantly correlated
with body weight or length, respectively.
Four organs show increases in percentage weights at all three periods: gonads,
lungs, liver and spleen. Two others have a n increase in post-metamorphosis: heart
and kidneys. The digestive tube and its parts and the pancreas have a relative decrease at the end of metamorphosis. The eyeballs are relatively largest in the postmetamorphosis, and smallest in the adults.
The metamorphosis of various species of
urodeles has been observed and studied for
many years, but this rather extensive literature will not be reviewed here. Grant
('30) has summarized much of the work
previous to her study, which presents the
sequence of the changes in the skin, the
atrophy of the caudal fin and the gills in
several species. She reports a good deal of
difference in the time required for metamorphosis, varying from 24 hours to a
week or ten days, in the several species.
She finds that amblystoma punctatum requires four or five days for the completion
of its metamorphosis.
The relationship between metamorphosis
and some of the endocrine glands has been
studied rather fully. DuShane and Hutchinson ('44) have reported the embryonic
growth of amblystoma, but no data have
been found in the literature on the quantitative anatomy of any of these salamanders in the periods immediately before and
after metamorphosis.
This study presents body weight, external measurements of the body and weights
and linear measurements of some of the
viscera of 97 tiger salamanders before
metamorphosis and 57, after metamorphosis. All were taken from the same pond in
the Grand Teton National Forest. These
data are compared with measurements of
adult amblystoma previously published
(Latimer, Roofe and Feng, '61).
MATERIALS AND METHODS
Over 500 salamanders (Amblystoma tigrinum malinosticum) were seined from
one of the smaller ponds (Moran) in
the Grand Teton National Forest in about
half an hour. They were brought into the
laboratory of the Jackson Hole Biological
Station and placed in tubs. The water was
changed daily, and they were fed aquatic
insects. Ninety-seven of these larval a m blystoma were weighed and the external
measurements made. Ten days later the
remaining specimens had completely metamorphosed and 57 of these metamorphosed
tiger salamanders were weighed and measured in a similar manner.
1 This investigation was supported in part by NIH,
GM 08537-02.
139
140
HOMER B . LATIMER AND PAUL GIBBONS ROOFE
The pre- and post-metamorphosis salamanders were all treated alike. Each specimen was anesthetized with MS 222 (Tricane methanesulfonate), weighed and the
ten external measurements made with a
sliding straight armed calipers reading to
0.1 mm. The body cavities were opened
and they were immersed in 10% formalin
and brought to Kansas. Here they were
changed to larger containers with an ample
supply of fresh 10% formalin solution and
held for over four months.
The specimens were weighed when
freshly anesthetized on a laboratory balance sensitive to 0.01 gm and here in
Kansas the entire amblystoma and each
of the individual organs were weighed in
glass stoppered weighing bottles on an
analytical balance sensitive to 0.1 mg. The
body weights were recorded to the nearest
milligram. The methods of making the external measurements are described in the
earlier report (Latimer, Roofe and Feng,
’61) and will not be repeated here. The
organs were dissected as free of the mesenteries as possible, and placed briefly in a
moist chamber until weighed. The lengths
and the weights of the entire digestive tube
are the sums of the measurements of its
four parts. The contents of the digestive
tube were not removed and the variable
amount of the contents is partially responsible for the high variability of the digestive
tube and its subdivisions. The lengths of
the three shorter divisions of the digestive
tube were measured with a sliding straight
armed calipers reading to 0.1 mm and the
lengths of the intestines were measured
with a metric ruler. These intestines of the
tiger salamanders were sufficiently pliable
so that they could be straightened out fully
for making these measurements. The
stomachs of 19 of the larval amblystoma
had been opened for a study of their contents and hence the weights of the stomach
and the entire digestive tube are reported
for only 78 larval amblystoma. The gall
bladders contained a variable amount of
secretion. The weights of the gall bladders
and their contents are included in the
weights of the livers.
The specimens were collected, weighed
and the external measurements were all
made by one person (P. G . R.) and the
dissections and measurements of the or-
gans were all made by the other author
(H. B. L.) and he is responsible for the
preparation and presentation of all of the
data.
Weights and percentage weights
The body weight and the weights of the
organs are shown in panel A of table 1.
The “L” or “ M preceding the “t” values in
the last column indicate that the measurement of the larval ( L ) or the metamorphosed (M) amblystoma is heavier or
forms a larger percentage of body weight
(panel B). The fresh body weight shown
in the first line was made immediately
after the amblystoma were anesthetized
and before any preservation. The second
line has the weight of the entire animal
after preservation in 10% formalin for
four months. Both the fresh and the preserved weights are significantly heavier in
the larvae than in the metamorphosed amblystoma, as shown in the last column.
The preserved larval amblystoma average
5.66% heavier than the fresh larvae while
the preserved metamorphosed amblystoma
average 8.52% lighter than the fresh metamorphosed amblystoma. Thus the preservation increases the body weight in the
larvae but decreases it in the metamorphosed animals. Both groups were treated
in the same manner and weighed on the
same balances. Hence there must be some
differences in the constitution of the two
groups which makes them react differently
to the formalin. Further study of the quantitative effects of preservation upon the organs and tissues is needed to clarify this.
There was an apparent reduction in the
loose areolar subdermal tissue in the metamorphosed specimens, with the skin more
closely adherent to the underlying musculature; also there was less loose areolar
tissue throughout the metamorphosed amblystoma.
All of these weights are more variable in
the larvae than in the metamorphosed
salamanders except the weights of the
pancreas and the gonads. The pancreas is
not encapsulated and it was very difficult
to remove it accurately and hence these
weights are not too significant. The sex of
the gonads was not determined in either
group, but the gonads are significantly
heavier in the metamorphosed specimens.
MEASUREMENTS, TIGER SALAMANDER
141
TABLE 1
Weights in grams and as percentages of body weight. The “t” values of 2.00 and above are significant
at 5 % , and values at 2.66 and above are significant at 1%
97 Larval amblystoma
Average and
stand. dev.
Coef. of
variation
57 Metamorphosed amblystoma
Coef..of
Average and
stand. dev.
Body wt. (fresh)
Body wt. (formal.)
Heart
Lungs
Digestive tube
Esophagus
Stomach
Intestines
Cloaca
Liver
Pancreas
Spleen
Kidneys
Gonads
Eyeballs
Brain
Panel A Weights in grams
5.65 21.20
21.18
4.46 k0.64
5.97 21.12
18.76
4.08 20.54
28.06
0.0260f 0.0056
0.0261 20.0073
39.01
0.0389f 0.0105
0.0362f0.0141
0.4487k0.2115 I
47.13
0.1974f0.0401
0.0163k0.0059
36.47
0.0049k 0.0015
0.157720.1239
78.55
0.066720.0179
0.208020.0726
34.92
0.0727f0.0160
0.0925f 0.0508
54.87
0.0531f 0.0186
0.169320.0487
28.77
0.149220.0332
0.011720.0045
38.81
0.0069k0.0028
0.006520.0024
36.57
0.0046f0.0008
0.031420.0101
32.11
0.0307f 0.0058
0.012520.0062
49.79
0.015220.0083
0.0177~0.0030
16.84
0.01612 0.0024
12.47
0.0318& 0.0033
0.032120.0040
14.29
13.14
21.59
26.92
20.33
29.92
26.90
22.06
35.10
22.27
40.83
18.42
18.82
54.71
15.17
10.46
Heart
Lungs
Digestive tube
Esophagus
Stomach
Intestines
Cloaca
Liver
Pancreas
Spleen
Kidneys
Gonads
Eyeballs
Brain
Panel B Percentages of body weight
0.436 20.113
26.05
0.640 k0.131
0.604 20.184
30.49
0.954 20.222
7.474 22.197
29.40
4.864 20.915
0.267 20.081
30.53
0.121 fO.036
2.554 21.391
54.45
1.636 20.392
3.216 20.745
23.18
1.794 20.380
1.437 20.650
45.24
1.312 f0.470
2.794 20.586
20.97
3.636 20.510
0.199 fO.077
38.51
0.168 20.062
0.106 20.038
35.22
0.114 fO.017
0.523 20.120
23.06
0.754 20.114
0.207 k0.096
46.29
0.366 20.185
0.302 f0.052
17.13
0.397 20.061
0.552 20.095
17.26
0.787 f0.088
20.46
23.22
18.81
29.89
23.94
21.21
35.80
14.03
37.00
14.99
15.19
50.42
15.40
11.14
1 Weights
“t”
variation
L 6.91
L 11.90
L 0.09
M 1.27
L 8.79
L 14.13
L 5.63
L 13.78
L 5.63
L 2.74
L 7.19
L 5.88
L 0.48
M 2.29
L 3.41
L 0.48
M 10.10
M 10.60
L 8.39
L 12.55
L 4.81
L 13.10
L 1.33
M 8.96
L 2.58
M 1.53
M 11.61
M 6.99
M 10.23
M 15.24
of 78 specimens only.
Their weight in these specimens has the
highest coefficient of variation in this group
and the highest in the entire table 1 with
the exception of the stomach and cloaca in
the larvae. This is evidently due to the beginning of their growth in some of the animals while in others the gonads remained
small, as in the larvae.
The right and left gonads were not
weighed separately but it was observed that
the left gonad was appreciably larger in
some of the amblystoma after metamorphosis and the smaller right gonad was frequently divided into two or three segments,
or fusiform masses, but always apparently
connected. This larger left gonad in these
salamanders is interesting when one recalls that only the left ovary is developed
in birds. In a study of the growth of 100
Leghorn chickens (Latimer, ’24) only one
bird was found with a small rudimentary
mass on the right side where the ovary
should have been located. A further study
of the size of the right and left ovaries in
adult amblystoma would be interesting.
None of the gonads was examined microscopically. The weights of the gonads in
the metamorphosed specimens were plotted
to see if they would form a bimodal curve,
but the distribution was only very scattered
with no appreciable double trends. Evidently a few of these glands had just begun to develop. This irregular growth in
the gonads is also indicated in their larger
coefficients of variation in the post-metamorphosed animals.
The greatest variability is evident in the
digestive tube and its subdivisions, espe-
142
HOMER B. LATIMER AND PAUL GIBBONS ROOFE
cially in the larvae. This may be accounted
for, very largely, by the variable amount of
material contained within the tube. In rabbits, with a closely regulated supply of
food, the contents of the digestive tube is
highly variable (Latimer and Sawin, '55).
As is to be expected, the brain is the most
constant in weight in both groups of these
salamanders. The average of all of the
coefficients of variation in the larvae is
35.62% and in the post-larval, 24.43%.
Panel B, table 1 has the weights of the
various organs expressed as percentages of
the body weight (preserved body weight).
These percentages, as expected, are less
variable than the weights in grams in panel
A. The average of the coefficients of variation for the larvae is 31.27%, which is a
reduction of 12.21% from the average of
the weights in panel A. The average for
the metamorphosed specimens is 23.68%,
or 3.07% less than the average for the
weights in grams. These percentages, like
the weights in panel A, are much less variable in the metamorphosed salamanders.
The coefficients of variation for the percentage weights of the eyeballs and brain
in both groups are larger than for their
weights in grams. This confirms earlier
findings that the central nervous system develops to its normal size more or less irrespective of body weight (Latimer and
Sawin, '58). These coefficients of their
percentage weights are the lowest in the
larval salamanders and the percentage
weight of the brain in the post-metamorphosed specimens has the lowest coefficient
in panel B. The liver, spleen and kidneys
have slightly lower coefficients than the
eyeballs in these older salamanders.
The two most variable organs in both
groups are the cloaca and the gonads. The
cloaca's variability is due probably to its
variable contents and that of the gonads
would be less if these animals had been
divided as to sex, for the ovaries are larger
in older salamanders, as well as in mammals (Latimer, Roofe and Feng, '61, and
Latimer, '56). The percentage weight of
the stomach in the larvae has the highest
coefficient in this panel, due without doubt
to its variable contents.
Six of these percentage weights are
larger in the larvae and these are the digestive tube and its subdivisions and the
pancreas. The other eight organs are
relatively heavier in the metamorphosed
salamanders.
These percentage weights indicate that
there are some differences between the preand post-metamorphosis amblystoma. The
larvae seem to have relatively larger digestive tubes, while the heart, lungs, liver,
kidneys, eyeballs and brain comprise a
larger proportion of the entire body weight
in the metamorphosed specimens. One
would expect to find relatively heavier
gonads in the older animals.
Hoskins and Hoskins ('19) have made
an exhaustive study of the effect of the
thyroid gland at time of metamorphosis in
the frog. They record their observations
upon the change in size of the organs in
the control, or nonoperated, frog (Rana
sylvatica). They report a decrease in body
weight and a decrease in actual size of the
heart, liver, spleen and kidneys, but all of
these organs are relatively heavier after
metamorphosis, due to the greater decrease
in the body weight. They find that the left
gonads in the frog are usually larger than
the right. Thus their observations suggest
that the changes in the frog and the tiger
salamander during metamorphosis are
alike in many respects.
Linear measurements in millimeters and
as percentages of body length
The body, or nose-anus length is shown
in the first line of panel A, table 2. This
measurement was used to determine all of
the percentage lengths in panel B. The
total length from tip of nose to tip of tail is
given in the second line. The difference
between these two dimensions is the length
of the tail. This averages 42.10 mm in the
larvae and 39.38 mm in the post larval
specimens, or a reduction of 6.5% .
The last column of panel A shows that
there are no significant differences in either
of these body lengths in the two groups of
salamanders. There are only two measurements in panel A significantly greater in
the metamorphosed amblystoma, namely:
the lengths of the two pairs of extremities.
There are four external measurements significantly greater in the larvae, and all of
these are transverse dimensions. The larval specimens have been shown to be
heavier (table 1) and now we see that they
143
MEASUREMENTS, TIGER SALAMANDER
are broader but not significantly different
in body length from the metamorphosed
animals.
Most of the external measurements are
less variable than the linear measurements of the digestive tube and its subdivisions. The average of the coefficients
of variation of the external measurements
in the larvae is 9.94% and for the digestive
tube, 15.14%. The comparable averages in
the metamorphosed amblystoma are respectively, 6.42% and 14.32%. Thus all
of these measurements are less variable in
the amblystoma after metamorphosis. This
decrease in the variability of the external
measurements may be accounted for, to a
degree, by the reduction of the subdermal
areolar tissue which would make the external measurements more easily and accurately determined in the metamorphosed
amblystoma. The average of all of the
coefficients in the larvae is 11.67% and
for the older specimens, 9.05%. Thus all
of the dimensions are less variable in the
older group.
The most variable dimension in both
groups is the length of the esophagus. It
is very short and not sharply demarked
from the pharynx or the stomach. The
other parts of the digestive tube were easily
separated from one another. The most
variable of the external measurements are
the widths of the body at the belly and the
pelvic width.
Panel B, table 2 has the linear measurements from panel A changed to percentages of the body, or nose-anus, length. The
variability of these percentages of body
length is slightly less than that for the
lengths in millimeters. The average of all
TABLE 2
Linear measurements in millimeters and as percentages of body (nose-anus) length. The “t” values
have the same significance as in table 1
97 Larval amblystoma
Average and
stand. dev.
Panel A
Coef. of
variation
57 Metamorphosed amblystoma
Average and
stand. dev.
“t”
Coef. .of
vanation
Measurements in millimeters
Body length
(nose - anus)
Body length
(snout - tip of tail)
Jaw length
Jaw width
Biocular diam.
Fore limb
Hind limb
Pectoral width
Belly width
Pelvic width
Dig. tube length
Esophagus
Stomach
Intestines
Cloaca
56.532 3.80
6.72
57.482 2.49
4.34
97.63% 6.01
13.74f 1.53
14.602 1.44
10.632 0.88
16.602 1.47
17.622 1.49
9.802 1.04
10.542 1.32
3.172 0.53
151.50221.55
3.812 0.66
19.142 2.66
115.41f19.21
13.112 1.79
6.15
11.12
9.86
8.27
8.84
8.46
10.66
12.50
16.78
14.22
17.22
13.91
16.64
13.69
96.862 4.31
13.63+-0.94
12.792 0.61
10.422 0.58
17.282 1.10
18.872 1.11
9.482 0.71
9.732 1.00
2.852 0.23
107.11% 14.28
2.192 0.44
15.672 1.48
76.64212.91
12.61-r-1.47
4.45
6.94
4.74
5.60
6.40
5.90
7.46
10.26
8.11
13.33
20.13
9.45
16.99
11.68
L
L
L
L
M
M
L
L
L
L
L
L
L
L
0.84
0.50
8.97
1.61
3.01
5.20
2.04
3.99
4.28
13.83
16.47
8.99
13.46
1.78
Jaw length
Jaw width
Biocular diam.
Fore limb
Hind limb
Pectoral width
Belly width
Pelvic width
Dig. tube length
Esophagus
Stomach
Intestines
Cloaca
Panel B Percentages of body (nose-anus) Iength
23.752 1.30
24.35f 2.68
11.00
22.26f 0.89
10.52
25.892 2.72
18.122 0.73
7.68
18.882 1.45
30.072 1.69
9.49
29.452 2.79
32.832 1.61
31.252 2.76
8.82
16.502 1.14
10.16
17.362 1.76
16.922 1.55
18.712 2.44
13.07
4.952 0.34
5.622 0.95
16.89
186.15222.00
7.42
266.67f 19.78
3.812 0.75
6.702 1.04
15.58
27.242 2.15
33.792 4.94
14.60
133.13f20.54
203.602 10.89
5.35
21.962 2.57
23.002 3.10
13.48
5.47
4.01
4.04
5.61
4.90
6.92
9.15
6.97
11.82
19.65
7.90
15.43
11.69
L
L
L
M
M
L
L
L
L
L
L
L
L
1.55
9.70
3.70
1.51
3.92
3.28
4.94
5.10
23.31
16.48
9.44
27.61
2.13
M 1.68
144
HOMER B. LATIMER AND PAUL GIBBONS ROOFE
of the coefficients of variation for the larvae is 11.08% and for the amblystoma
after metamorphosis, 8.74%. This is a
reduction of 5% and 3% respectively. As
in the preceding panel, the external measurements are less variable than the linear
measurements of the digestive tube. The
average of the coefficients of variation for
the percentages of the digestive tube is
11.29% in the larvae and 13.30% for the
metamorphosed specimens. The average
of the coefficients for the external measurements is 10.95% for the larvae and
5.88% for the amblystoma after metamorphosis. Changing the measurements of
length to percentages of body length usually reduces their variability, and all of
these except the external measurements in
the larvae are less variable as percentages
of body length. An explanation for the
increase in these percentages of the external dimensions in the larvae is possibly
the greater variability of the body length
in the larvae.
The length of the jaws is not significantly different in the two groups, but the
width of the jaws in the amblystoma after
metamorphosis is reduced both in length in
millimeters and in relative length. The
lengths of the limbs are the only percentage
values which are larger in the metamorphosed specimens, although the fore limbs
are only slightly longer. Thus the relative
length of the hind limb is the only dimension significantly greater in the older amblystoma.
The digestive tube and its subdivisions
are all longer in the larvae, both in milli-
meters and as percentages of body length,
but how much of this is due to the greater
amount of food in the larval digestive tube
is unknown. The percentage length of the
entire tube is relatively 30% shorter in the
older specimens. The greatest difference is
in the length of the intestines for these are
35% shorter in the metamorphosed amblystoma. Does this indicate a change in
the type of food in these amblystoma similar to that known to occur in some frogs?
Briefly, the hind limbs are relatively
longer in the salamanders after metaniorphosis, the body length is not significantly
changed and the transverse diameters are
relatively shorter, including the width of
the jaws. Thus the metamorphosed salamander is a more slender animal than the
larval, with longer legs and narrower jaws.
Percentages of digestive tube
For a better understanding of the relative proportions of the subdivisions of the
digestive tube, the weights and lengths of
its four subdivisions were changed to percentages of the weight or length of the
entire tube and these percentages are
shown in table 3. The relative weights are
in panel A and the lengths, in panel B.
The lowest coefficients of variability are
for the weights and lengths of the intestines, but when one considers that the intestines comprise about 40% of the weight
and 75% of the length of the digestive
tube, this is not surprising. The percentage
weights and lengths of the esophagus are
the most variable. Its size and difficulty of
accurate separation from adjacent parts
TABLE 3
Weights and linear measurements as percentages of the weight or length of the digestive tube. The
“t” values are the same as in table 1
78 Larval amblystoma
Average and
stand. dev.
Coef. of
variation
57 Metamorphosed amblystoma
Average and
stand. dev.
“t”
Coef. of
variation
Esophagus
Stomach
Intestines
Cloaca
Panel A Percentage weights
3.722 1.23
33.07
2.532 0.74
19.43
33.802 5.26
33.39 6.49
43.86’5.79
13.20
37.01t4.19
34.47
26.65t6.24
19.02f.6.56
29.19
15.55
11.33
23.41
L
M
L
M
Esophagus
Stomach
Intestines
Cloaca
Panel B Percentage lengths
2.6020.53
20.58
2.082 0.50
12.5921.65
13.11
14.77* 1.59
75.99 22.71
3.57
71.23+-3.00
8.8221.36
15.42
11.922 1.72
23.86
10.77
4.21
14.40
L 5.67
M 7.57
’
6.39
0.39
7.47
6.71
L 9.47
M 11.51
145
MEASUREMENTS, TIGER SALAMANDER
has been mentioned above. These may at
least contribute to its high coefficient of
variability.
As in the two preceding tables, the intestines are significantly heavier and longer in
the larval amblystoma. In both panels of
this table, the esophagus and the intestines
are significantly heavier and longer in the
larvae, while the stomach and cloaca are
larger relatively in the salamanders which
have undergone metamorphosis. This contributes additional evidence that there is a
change in the proportions of the digestive
tube during metamorphosis.
were more easily and accurately measured
because of the decrease in the subdermal
loose tissue. On the whole these weights
and linear measurements will predict body
weight or body length, respectively, with
a fair degree of accuracy.
Correlations with body weight
and body length
The coefficients of correlation between
the measurements and body weight and
body (nose-anus) length are shown in
table 4. AU of the correlations in this table
are significant at the 5% level or above.
All of the ponderal correlations in panel
A, except the weight of the pancreas in the
larval salamanders are significant at the
1%level. Seven of the ten correlations are
higher in the larval salamanders than in
the post metamorphosis specimens. All of
the weights of the organs are rather well
correlated with body weight in both series
of these amblystoma.
The correlations of the linear measurements of the larvae in panel B, table 4 are
all significant at the 5% level and all except three transverse dSmensions (jaw
width, biocular diameter and belly width)
are significant at 1 % . All of the linear
measurements of the metamorphosed salamanders are significantly correlated with
body length, and all except one (pelvic
width) are significant at 1 % .
In general, these weights and linear
measurements are well correlated with
body weight or body length respectively.
Those measurements with lower correlations are organs with very high variability
such as the pancreas, which was very hard
to remove accurately. Some of the transverse dimensions have low coefficients of
correlation, but these are naturally variable
(belly width), or difficult to measure accurately (pelvic width), The linear correlations of the external measurements are
generally higher in the metamorphosed
animals. It has been suggested that these
Heart
TABLE 4
Coeficients of Correlation with body weight
and body length (nose-anus)
97
Larval
amblystoma
Panel A
Lungs
Dig. tube
Liver
Pancreas
Spleen
Kidneys
Gonads
Eyeballs
Brain
Panel B
Jaw length
Jaw width
Biocular
Fore limb
Hind limb
Pectoral width
Belly width
Pelvic width
Dig. tube leng.
Weights
0.615
0.711
0.695
0.816
0.257
0.570
0.724
0.568
0.589
0.354
57
Metamorphosed
amblystoma
0.454
0.640
0.442
0.812
0.384
0.648
0.598
0.462
0.405
0.599
Linear measurements
0.858
0.622
0.247
0.665
0.237
0.649
0.642
0.661
0.366
0.521
0.390
0.446
0.225
0.423
0.336
0.263
0.599
0.495
“t” Values for the larval of 2.00 and above are
significant at 5% and values of 2.60 and above are
significant at 1%.
“t” Values for the .metamorphosed amblystoma of
2.61 and above are significant at 5% and 3.40 and
above are significant at 1%.
Comparison of pre- and postmetamorphosis and
adult stages
The only known study of the growth of
the salamander is that by DuShane and
Hutchinson (’44) and they studied only
the larval growth in salamanders. Data
similar to the present data, but from mature tiger salamanders, have been published (Latimer, Roofe and Feng, ’61).
These adult salamanders were collected
from three separate ponds and the specimens from one pond differed significantly
from the other two ponds. These three
ponds and the pond from which the present
specimens were collected are all in the
Teton National Forest and not too far from
the Jackson Hole Biological Station. The
146
HOMER B. LATIMER AND PAUL GIBBONS ROOFE
averages of the weights and percentage
weights of the specimens in the earlier report are used in making these comparisons.
The average body weight of the mature
salamander is 8.9 times that of the post
metamorphosis animal and there are four
organs which increase at nearly the same
rate. These organs together with their
multiples of increase are: eyeballs (6.2
times), heart (7.4 times), kidneys (7.8
times) and the lungs (9.8 times). The
increase in the eyeballs suggests that in
the amblystoma as in most mammals the
central nervous system is precocious in its
development.
The liver increases 13.7 times during
this period and the entire digestive tube,
17.1 times. Following in order are, the
pancreas with an increase of 22.5 times
and the spleen with a n increase of 30.4
times. The greatest increase is found in
the gonads which increase 57.9 times.
However, this is expected for these animals
have become sexually mature in this
period.
Changing the weights of the organs to
percentages of body weight, possibly will
make these comparisons more clear. The
averages of the percentages from the preceding report will be used. The digestive
tube and its subdivisions and the pancreas
increase in their relative weights from the
larvae to the mature salamanders, but they
all manifest a decrease in relative weight
in the post metamorphosis period. The
decrease in the amount of the contents of
the digestive tube may account for at least
some of this decrease and may also account for a part of the decrease in the
weight in grams of the entire body.
There are four organs which suggest a
continuous growth, for they show an increase at each of these stages. These are:
gonads, lungs, liver and spleen. Two organs which increase from larval to adult,
but have an increased percentage of body
weight in the post metamorphosis stage,
are the heart and the kidneys. The eyeballs are unique in that they decrease from
the larval to the adult amblystoma, but
have their maximum percentage weight in
the post metamorphosis period.
Again, these are merely the weights and
percentage weights at three periods of the
entire growth and they do not replace a
real growth study of the tiger salamander
which is needed. They are presented in
lieu of anything more complete.
The eight external linear measurements
show interesting changes as well as the
ponderal measurements. The average body
length from the tip of the nose to the tip
of the tail increases two times from metamorphosis to maturity. There are five measurements which increase less than the body
length and these and their multiples of
increase are: jaw length and length of
fore limb, both of which increase 1.6 times;
the biocular and the jaw width, both 1.7
times; and the hind limb, 1.8 times.
Increasing more than the body length
are the length of the entire digestive tube,
2.5 times; pectoral width, 2.4 times; belly
width, 3.04 times, and pelvic width, 3.9
times. These measurements of total growth
suggest that the head and the length of the
two pairs of extremities are smaller in the
adult while the length of the digestive tube
and the width of the body are larger in the
adult.
Changing the eight l i n e z measurements
to percentages of body length will make
the differences in these salamanders more
evident. These lengths are shown in panel
B, table 2 as percentages of nose-anus
length while in table 3 of the earlier report
(Latimer, Roofe and Feng, '61), they are
expressed as percentages of nose-tip of
tail. To better compare these percentages
the lengths of the linear measurements of
the present series have been changed to
percentages of nose-tip of tail dimension.
The three new percentages (not shown
in table 2, panel B) of the head region
decrease from their maxima in the larvae
to their minima in the adults, indicating
the head is relatively largest in the larvae
and smallest in the adults. The relative
length of the digestive tube is the largest
in the larvae decreasing to its minimum
in the amblystoma after metamorphosis
and then increasing somewhat in the
adults. Thus although the digestive tube
is relatively heaviest in the adults it is
relatively longest in the larval amblystoma.
The three transverse diameters of the body
are the shortest relatively in the amblystoma after metamorphosis and longest in
the adult. This wider body in the adults
with reference to length would accommo-
MEASUREMENTS, TIGER SALAMANDER
147
Latimer, H. B. 1924 Postnatal growth of the
body, systems and organs of the single comb
White Leghorn chicken. J. Agri. Res., 29:
363-397.
1956 The ponderal growth of the ovaries
and uterus in the fetal dog. Anat. Rec., 225:
731-744.
Latimer, H.B., P. G. Roofe and L. S. Feng 1961
Weights and linear measurements of the body
and of some of the organs of the tiger salamanLITERATURE CITED
der. Anat. Rec., 141: 35-44.
DuShane, G. F., and C. Hutchinson 1944 Differences in size and developmental rate between Latimer, H. B., and P. B. Sawin 1955 Morphogenetic studies of the rabbit. XII. Organ size
Eastern and Midwestern embryos of Amblyin relation to body weight in adults of small
stoma maculatum. Ecology, 25: 414-423.
sized race X. Anat. Rec., 223: 81-102.
Grant, M.P. 1930 Diagnostic stages of urodele
1958 Morphogenetic studies of the rabmetamorphosis. Anat. Rec., 45: 1-25.
bit. XX. A comparison of the weights of the
Hoskins, E. R., and M. M. Hoskins 1919 Growth
brain and of its parts in a large and in a small
and development of amphibia as affected by
race of rabbits. Anat. Rec., 132: 619-632.
thyroidectomy. J. Exp. Zool., 29: 1-69.
date the relatively heavier internal organs
as described above. The two pairs of extremities are relatively longest immediately
after metamorphosis.
Thus the adult salamander has a relatively smaller head, shorter limbs and a
more robust body.
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