4. THE CIRCULATORY SYSTEM
159
and Randall, 1967b; Stevens and Randall, 1967b), the dye dilution
method (Murdaugh et al., 1965), and the direct measurement of the
velocity of blood flow in the ventral aorta using either an electromagnetic
(Satchel1 and Jones, 1967) or a Doppler ultrasonic blood flowmeter
system (Johansen et al., 1966).
Recorded values of cardiac output in a number of elasmobranchs are
in the region of 25 ml/kg/min. The fish investigated include dogfish,
Squalas acanthias (Murdaugh et al., 1965; Robin et al., 1964) and
Scyliorhinus stellaris (Piiper and Schumann, 1967). Hanson (1967) reported cardiac outputs for the dogfish, Squalus suckbyi, of between 9
and 23 ml/kg/min. 'The cardiac output of the ratfish, Hydrolagus colliei,
is about 21 ml/kg/min. Cardiac output per kilogram falls with increasing weight in the skate, Raja binocttlata.
By comparison, measured values for cardiac output in teleosts, are
variable, ranging from 5 to 100 ml/kg/min (Goldstein et al., 1964;
Johansen, 1962; Garey, 1967; Holeton and Randall, 1967b; Stevens and
Randall, 1967b; Randall, 1968). Most values, however, fall within the
range of 15-30 ml/kg/min.
Peak ejection velocities of blood flow in the ventral aorta of the Californian Horn shark ( Heterodontus francisci), skate ( Raja binoculata ),
and dogfish (Squalus suckleyi) are between 8 and 20 cm/sec (Johansen
et al., 1966; Hanson, 1967) which occur 120 msec after the aortic valves
open in the Horn shark and 450 msec in the skate; acceleration of the
blood reaches a maximum of 120 cm/sec2 in the Horn shark.
B. Blood Volume
The blood volume of a fish consists of that portion of the extracellular
space contained within the cardiovascular system, plus the volume of
erythrocytes, leukocytes, and platelets in the blood. It consists of a
plasma volume and the volume of cells within the blood, which when
expressed as a percentage of the total blood volume is the hematocrit.
Both plasma volume and hematocrit vary considerably in fish.
Mott (1957) has reviewed the earlier literature on blood volume
measurements in fish. Holmes and Donaldson (1969) have recently completed an exhaustive review of the subject which will only be discussed
briefly here. Thorson (1958, 1959, 1961, 1962) has estimated blood
volume from measurements of plasma volume and hematocrit in a large
number of fish. Agnatha have very large blood volumes in excess of any
other fish. The blood volume of Chondrichthyes is about 6.6% body
weight, whereas that of Chondrostei, Holostei, and teleosts (both marine
159
and Randall, 1967b; Stevens and Randall, 1967b), the dye dilution
method (Murdaugh et al., 1965), and the direct measurement of the
velocity of blood flow in the ventral aorta using either an electromagnetic
(Satchel1 and Jones, 1967) or a Doppler ultrasonic blood flowmeter
system (Johansen et al., 1966).
Recorded values of cardiac output in a number of elasmobranchs are
in the region of 25 ml/kg/min. The fish investigated include dogfish,
Squalas acanthias (Murdaugh et al., 1965; Robin et al., 1964) and
Scyliorhinus stellaris (Piiper and Schumann, 1967). Hanson (1967) reported cardiac outputs for the dogfish, Squalus suckbyi, of between 9
and 23 ml/kg/min. 'The cardiac output of the ratfish, Hydrolagus colliei,
is about 21 ml/kg/min. Cardiac output per kilogram falls with increasing weight in the skate, Raja binocttlata.
By comparison, measured values for cardiac output in teleosts, are
variable, ranging from 5 to 100 ml/kg/min (Goldstein et al., 1964;
Johansen, 1962; Garey, 1967; Holeton and Randall, 1967b; Stevens and
Randall, 1967b; Randall, 1968). Most values, however, fall within the
range of 15-30 ml/kg/min.
Peak ejection velocities of blood flow in the ventral aorta of the Californian Horn shark ( Heterodontus francisci), skate ( Raja binoculata ),
and dogfish (Squalus suckleyi) are between 8 and 20 cm/sec (Johansen
et al., 1966; Hanson, 1967) which occur 120 msec after the aortic valves
open in the Horn shark and 450 msec in the skate; acceleration of the
blood reaches a maximum of 120 cm/sec2 in the Horn shark.
B. Blood Volume
The blood volume of a fish consists of that portion of the extracellular
space contained within the cardiovascular system, plus the volume of
erythrocytes, leukocytes, and platelets in the blood. It consists of a
plasma volume and the volume of cells within the blood, which when
expressed as a percentage of the total blood volume is the hematocrit.
Both plasma volume and hematocrit vary considerably in fish.
Mott (1957) has reviewed the earlier literature on blood volume
measurements in fish. Holmes and Donaldson (1969) have recently completed an exhaustive review of the subject which will only be discussed
briefly here. Thorson (1958, 1959, 1961, 1962) has estimated blood
volume from measurements of plasma volume and hematocrit in a large
number of fish. Agnatha have very large blood volumes in excess of any
other fish. The blood volume of Chondrichthyes is about 6.6% body
weight, whereas that of Chondrostei, Holostei, and teleosts (both marine