10. THE SWIM BLADDER AS A HYDROSTATIC ORGAN
427
advantage of such information two more parameters must be known.
One is the total pressure at which the fish was caught, the other is at
what pressure the swim bladder gas would have made the fish neutrally
buoyant. The first of these values is used to calculate the partial pressure
of each gas, the second gives the minimum pressure against which the
fish is able to deposit gas.
Biot (1807) was the first to analyze the gas of the swim bladder. He
constructed a gas analyzer where he mixed the unknown gas with
hydrogen, ignited the mixture, and weighed the resultant water. He was
primarily interested in variations of the composition of the atmosphere;
and possibly bored by its constancy, he introduced a sample of swim
bladder gas into his analyzer. Much to his delight, it is presumed, the
gas analyzer exploded. Biot reconstructed his gadget and confirmed the
high 0, content of the gas. More extensive analysis of swim bladder gases
from deep sea fishes was first reported by Schloesing and Richard in
1898. A typical example of their results in a specimen caught at 900-meter
depth was: oxygen 75.1% nitrogen 20.5%, carbon dioxide 3.1%, and argon
0.4%. Scholander and van Dam (1953) studied gas taken from the swim
bladders of fishes living at depths down to 1400 meters. The general
picture emerging from these and other studies is that in fishes living near
the surface the swim bladder contains a gas which is much like air, while
at greater depths 0, becomes an increasingly dominant component
(Fig. 9). In deep sea fishes the Po, and PN, in the bladder may be 100
and 25 atm, respectively, while the Po, and PNz of the ambient water,
and consequently of the arterial blood, does not exceed 0.2 and 0.8 atm,
respectively. The swim bladder has thus the ability to concentrate 0,
by a factor of at least 500 and N, by a factor of 30.
Almost a century after Biot’s experiments, Hufner (1892) published
the observation that the swim bladder of whitefish, Coregonus acronius,
from the bottom of Lake Constance at a depth of 60-80 meters contained 99!Z N,. Accordingly, the P,, in the bladder at the depth at which
the fish was caught must have been 7-9 atm. Similar findings on the
swim bladder gas of several other species of freshwater physostomes
from Lake Huron and Lake Michigan were later reported by Saunders
(1953), Tait (1956), Scholander et aE. (1956a), and Sundnes et al.
(1958). Sundnes (1963) added a significant piece of information when
he observed that high P,, in several species of physostomes was found
only in those fishes that had stayed for several weeks at the same depth.
In the same species he found high Po, values in samples taken from fishes
that had recently migrated to greater depths.
From the point of view of the mechanism of gas deposition the composition of freshly deposited gas has special interest. Unfortunately, such
427
advantage of such information two more parameters must be known.
One is the total pressure at which the fish was caught, the other is at
what pressure the swim bladder gas would have made the fish neutrally
buoyant. The first of these values is used to calculate the partial pressure
of each gas, the second gives the minimum pressure against which the
fish is able to deposit gas.
Biot (1807) was the first to analyze the gas of the swim bladder. He
constructed a gas analyzer where he mixed the unknown gas with
hydrogen, ignited the mixture, and weighed the resultant water. He was
primarily interested in variations of the composition of the atmosphere;
and possibly bored by its constancy, he introduced a sample of swim
bladder gas into his analyzer. Much to his delight, it is presumed, the
gas analyzer exploded. Biot reconstructed his gadget and confirmed the
high 0, content of the gas. More extensive analysis of swim bladder gases
from deep sea fishes was first reported by Schloesing and Richard in
1898. A typical example of their results in a specimen caught at 900-meter
depth was: oxygen 75.1% nitrogen 20.5%, carbon dioxide 3.1%, and argon
0.4%. Scholander and van Dam (1953) studied gas taken from the swim
bladders of fishes living at depths down to 1400 meters. The general
picture emerging from these and other studies is that in fishes living near
the surface the swim bladder contains a gas which is much like air, while
at greater depths 0, becomes an increasingly dominant component
(Fig. 9). In deep sea fishes the Po, and PN, in the bladder may be 100
and 25 atm, respectively, while the Po, and PNz of the ambient water,
and consequently of the arterial blood, does not exceed 0.2 and 0.8 atm,
respectively. The swim bladder has thus the ability to concentrate 0,
by a factor of at least 500 and N, by a factor of 30.
Almost a century after Biot’s experiments, Hufner (1892) published
the observation that the swim bladder of whitefish, Coregonus acronius,
from the bottom of Lake Constance at a depth of 60-80 meters contained 99!Z N,. Accordingly, the P,, in the bladder at the depth at which
the fish was caught must have been 7-9 atm. Similar findings on the
swim bladder gas of several other species of freshwater physostomes
from Lake Huron and Lake Michigan were later reported by Saunders
(1953), Tait (1956), Scholander et aE. (1956a), and Sundnes et al.
(1958). Sundnes (1963) added a significant piece of information when
he observed that high P,, in several species of physostomes was found
only in those fishes that had stayed for several weeks at the same depth.
In the same species he found high Po, values in samples taken from fishes
that had recently migrated to greater depths.
From the point of view of the mechanism of gas deposition the composition of freshly deposited gas has special interest. Unfortunately, such