306
THE BIOLOGY OF EUPHAUSIIDS
TABLE XXXI. GROWTH INCREMENTS (mg/day) OF
Species
Thysanopoda acutifrons
Euphausia triacantha
E . superba Bargmann 3
?
Ruud
Nemoto
Mauchline lMeganyctiphanes norvegica
Iceland
Clyde
Cadiz
Thysanoessa raschii Clyde
T . inermis
N. Iceland and Greenland
S. Iceland
T . Zongicaudata
Gulf stream
Greenland
T . longipes
0-group
Period
Days
May-Oct.
180
-
-
May-Oct.
150
Apr.-July
120
Jan.-Sept.
225
May-Oct.
180
J ~ e - O c t .
150
May-Oct.
180
May-Aug.
105
May-Aug.
105
May-Sept.
150
Rate
0.065
-
-
-
0.145
-
-
0.307
0.608
0.341
0.111
0.049
0.100
0.086
0-041
0.027
0-group
rate
0.200
0.129
0.156
0.086
0.073
0.178
Period
Feb.-A~g.
-
-
-
Nov.-Feb.
-
-
0.238
May-Aug.
0.378
Mar.-June
0.383
-
0.126
Apr.-July
0.040
May-Sept.
0'093
J ~ n e - J ~ l y
0.032
-
0.028
May-July
0.045
Apr.-Oct.
Apr.-Oct.
The growth curves in Pigs 115 and 116 all show decreased rates of
growth in length during the winter months while the gonads are
maturing and part of this decrease in rate of growth in length may
result from the metabolic demands of the gonads. The volume of the
ovary is about 10% of the volume of the animals and so the weight of
the mature ovary will be about 10% of the weight of the animal. The
ovary grows to its full weight in about 3 months. Thysanoessa
raschii, T . inermis, or Euphausia paci$ca of 20 mm body length
have mature ovaries weighing approximately 5 mg. The average
growth increment of this ovary would therefore have to be about
0.05 mg/day for it to mature in about 3 months. Similarly, the growth
increment of an ovary of E. superba of 50 mm body length would be
about 0.60 mg/day. Consequently, the average daily weight increments
of the ovary during the period of 3 months when it is maturing, are
equal to, or more than half, the daily weight increments of the animals
when they are not breeding but are growing in length. After breeding,
the gonads return to a rudimentary condition and do not mature again
until the period prior to the next breeding season.
The above theory requires confirmation because the growth of the
THE BIOLOGY OF EUPHAUSIIDS
TABLE XXXI. GROWTH INCREMENTS (mg/day) OF
Species
Thysanopoda acutifrons
Euphausia triacantha
E . superba Bargmann 3
?
Ruud
Nemoto
Mauchline lMeganyctiphanes norvegica
Iceland
Clyde
Cadiz
Thysanoessa raschii Clyde
T . inermis
N. Iceland and Greenland
S. Iceland
T . Zongicaudata
Gulf stream
Greenland
T . longipes
0-group
Period
Days
May-Oct.
180
-
-
May-Oct.
150
Apr.-July
120
Jan.-Sept.
225
May-Oct.
180
J ~ e - O c t .
150
May-Oct.
180
May-Aug.
105
May-Aug.
105
May-Sept.
150
Rate
0.065
-
-
-
0.145
-
-
0.307
0.608
0.341
0.111
0.049
0.100
0.086
0-041
0.027
0-group
rate
0.200
0.129
0.156
0.086
0.073
0.178
Period
Feb.-A~g.
-
-
-
Nov.-Feb.
-
-
0.238
May-Aug.
0.378
Mar.-June
0.383
-
0.126
Apr.-July
0.040
May-Sept.
0'093
J ~ n e - J ~ l y
0.032
-
0.028
May-July
0.045
Apr.-Oct.
Apr.-Oct.
The growth curves in Pigs 115 and 116 all show decreased rates of
growth in length during the winter months while the gonads are
maturing and part of this decrease in rate of growth in length may
result from the metabolic demands of the gonads. The volume of the
ovary is about 10% of the volume of the animals and so the weight of
the mature ovary will be about 10% of the weight of the animal. The
ovary grows to its full weight in about 3 months. Thysanoessa
raschii, T . inermis, or Euphausia paci$ca of 20 mm body length
have mature ovaries weighing approximately 5 mg. The average
growth increment of this ovary would therefore have to be about
0.05 mg/day for it to mature in about 3 months. Similarly, the growth
increment of an ovary of E. superba of 50 mm body length would be
about 0.60 mg/day. Consequently, the average daily weight increments
of the ovary during the period of 3 months when it is maturing, are
equal to, or more than half, the daily weight increments of the animals
when they are not breeding but are growing in length. After breeding,
the gonads return to a rudimentary condition and do not mature again
until the period prior to the next breeding season.
The above theory requires confirmation because the growth of the