276
THE BIOLOGY O F EUPRAUSIIDS
or through the oxygen minimum layers present in extensive areas of
the Pacific off the North and South American coasts.
McWhinnie and Marciniak (1964) attempted to investigate the
metabolism of fragments of tissues of E. superba by incubating tissue
slices with selected substrates and determining oxygen consumption at
2°C. Their results (Table XXIV) indicate the use of glucose and
pyruvate as oxidizable substrates and also that conventional citric acid
oxidations and electron transport take place in these animals. The
glucose stimulation of oxygen consumption in the tissues of E. superba,
according to these authors, is indicative of " greater substrate utilization via the Embden-Meyerhof and aerobic routes by cold-adapted
species than by species adapted to warmer temperatures ". When the
inhibitor iodoacetic acid was used at a concentration of 1 x
M,
there was no change in the oxygen consumption from that of the
control. If tissues of temperate crustaceans are treated with the same
concentration of the inhibitor, the oxygen consumption of the tissues is
approximately 36-51% lower than that of the control tissues for intermoult and premoult animals respectively.
An attempt has been made by Lasker (1960) to estimate the carbon
budget of E. paci$ca by using radioactive carbon-14. The results of
his experiments, which only extended over 24 hr, are shown in Table
XXV. 14C-labelled bacteria free cultures of the green algal flagellate,
Dunaliella primolecta Butcher, were used as food and E . pacijka, placed
in cultures dense enough to give coloration to the water, filtered out
enough algae to fill the stomach, digestive gland, and intestine in a very
short time. Faecal pellets were removed from the water and the
experimental animals, after washing in filtered sea water, were dissected
to obtain both their intestinal tracts and their digestive glands. Each
eviscerated animal was dried, weighed and combusted to carbon dioxide
for assay of total carbon. Table XXV gives the carbon balances found
in eight individuals at different algal densities, and the efficiencies with
which these individuals absorbed carbon into their tissues are calculated.
The carbon incorporation efficiency is the percentage of the carbon
ingested which is absorbed into the tissues during short-term feeding
experiments and ranged from 11-3 to 73.6%. This included the carbon
absorbed by the cuticle and therefore destined to be lost st moulting.
Lasker made a further series of experiments extending over many days
(Table XXVI) and determined the amounts of assimilated carbon which
are incorporated into the tissues through growth, lost from the animal
at moulting and in reproductive products, and respired as carbon
dioxide. The amount of carbon assimilated when growth is rapid may
be as high as 30% (Table XXVI) but can be as little, under slower rates
THE BIOLOGY O F EUPRAUSIIDS
or through the oxygen minimum layers present in extensive areas of
the Pacific off the North and South American coasts.
McWhinnie and Marciniak (1964) attempted to investigate the
metabolism of fragments of tissues of E. superba by incubating tissue
slices with selected substrates and determining oxygen consumption at
2°C. Their results (Table XXIV) indicate the use of glucose and
pyruvate as oxidizable substrates and also that conventional citric acid
oxidations and electron transport take place in these animals. The
glucose stimulation of oxygen consumption in the tissues of E. superba,
according to these authors, is indicative of " greater substrate utilization via the Embden-Meyerhof and aerobic routes by cold-adapted
species than by species adapted to warmer temperatures ". When the
inhibitor iodoacetic acid was used at a concentration of 1 x
M,
there was no change in the oxygen consumption from that of the
control. If tissues of temperate crustaceans are treated with the same
concentration of the inhibitor, the oxygen consumption of the tissues is
approximately 36-51% lower than that of the control tissues for intermoult and premoult animals respectively.
An attempt has been made by Lasker (1960) to estimate the carbon
budget of E. paci$ca by using radioactive carbon-14. The results of
his experiments, which only extended over 24 hr, are shown in Table
XXV. 14C-labelled bacteria free cultures of the green algal flagellate,
Dunaliella primolecta Butcher, were used as food and E . pacijka, placed
in cultures dense enough to give coloration to the water, filtered out
enough algae to fill the stomach, digestive gland, and intestine in a very
short time. Faecal pellets were removed from the water and the
experimental animals, after washing in filtered sea water, were dissected
to obtain both their intestinal tracts and their digestive glands. Each
eviscerated animal was dried, weighed and combusted to carbon dioxide
for assay of total carbon. Table XXV gives the carbon balances found
in eight individuals at different algal densities, and the efficiencies with
which these individuals absorbed carbon into their tissues are calculated.
The carbon incorporation efficiency is the percentage of the carbon
ingested which is absorbed into the tissues during short-term feeding
experiments and ranged from 11-3 to 73.6%. This included the carbon
absorbed by the cuticle and therefore destined to be lost st moulting.
Lasker made a further series of experiments extending over many days
(Table XXVI) and determined the amounts of assimilated carbon which
are incorporated into the tissues through growth, lost from the animal
at moulting and in reproductive products, and respired as carbon
dioxide. The amount of carbon assimilated when growth is rapid may
be as high as 30% (Table XXVI) but can be as little, under slower rates