9. INTERNAL ANATOMY AND PHYSIOLOGY
271
L
) A
*
moulted. Mackintosh (1967) has published some data, obtained at
South Georgia in 1930, on moulting of Euphausia superba. The animals
were maintained singly in 7 lb specimen jars which were kept in darkness
in wooden boxes partitioned and lined with felt. The water temperature
in the jars was not measured regularly but probably ranged from about
1-4' to about 3.5"C ; the animals did not appear to feed and no noticeable increases in body length occurred when individuals moulted. Under
l
l
,
,
l
l
1
I
1
-
5 0
100
Time (days)
14
16
d
150
FIG. 104. The intermoult periods of an individual Euphausia paci$ca related to tempera(After Lasker,
ture. Broken line, temperature ; solid line, moulting frequency.
1966.)
these conditions, E . superba moulted about once every 14 days but this
intermoult period may be shorter when the animals are feeding and
active growth in size is taking place. Paranjape (1967) found that
E. pacijcica, Thysanoessa spinifera, T . raschii, T . longipes (unspined
form = T . inspinata), and Tessarabrachion oculatum moulted a t 4-6
day intervals at l1°-15"C. The average dry weight of the moults of
the first three species named was 5.92-9.39% of the dry body weight
while the organic content of the moult was 7 3 4 3 % of the dry wt of the
moult.
Lasker (1960) examined the oxygen consumption of Euphausia
pacifica and later (Lasker, 1966) published the results of further experi-
271
L
) A
*
moulted. Mackintosh (1967) has published some data, obtained at
South Georgia in 1930, on moulting of Euphausia superba. The animals
were maintained singly in 7 lb specimen jars which were kept in darkness
in wooden boxes partitioned and lined with felt. The water temperature
in the jars was not measured regularly but probably ranged from about
1-4' to about 3.5"C ; the animals did not appear to feed and no noticeable increases in body length occurred when individuals moulted. Under
l
l
,
,
l
l
1
I
1
-
5 0
100
Time (days)
14
16
d
150
FIG. 104. The intermoult periods of an individual Euphausia paci$ca related to tempera(After Lasker,
ture. Broken line, temperature ; solid line, moulting frequency.
1966.)
these conditions, E . superba moulted about once every 14 days but this
intermoult period may be shorter when the animals are feeding and
active growth in size is taking place. Paranjape (1967) found that
E. pacijcica, Thysanoessa spinifera, T . raschii, T . longipes (unspined
form = T . inspinata), and Tessarabrachion oculatum moulted a t 4-6
day intervals at l1°-15"C. The average dry weight of the moults of
the first three species named was 5.92-9.39% of the dry body weight
while the organic content of the moult was 7 3 4 3 % of the dry wt of the
moult.
Lasker (1960) examined the oxygen consumption of Euphausia
pacifica and later (Lasker, 1966) published the results of further experi-