Table 1.2 Distribution of water in the body of various vertebrates
et 100 g body weight
Total
Extracellular
ln trabody water
space
cellular
Plasma interstitial Total
Agnatha
Petrom yzon marinusl
75.6
5.5
18.4
23.9
51.7
(Lake lamprey)
Chondrichthyes
Carcharhinus
nicaraguensisl
FW
72.1
5.1
14.6
19.7
52.4
(F. W. shark)
Squalus acanthias'
SW
71.7
5.5
15.7
21.2
50.5
(Spiny dogfish)
Osteichthyes
Chondrostei
Polyodon spathula 3
FW
74.0
2.2
13.4
15.6
58.4
(Paddlefish)
Holostei
Amia calva 3
FW
74.5
2.2
16.7
18.9
55.6
(Bowfin)
Teleoste i
Cyprinus carpio'
FW
74.1
1.8
13.7
15.5
55.9
(Carp)
Parrot fish
SW
73.1
2.4
14.2
16.6
56.5
Reptilia
AmphiboLurusornatust T
73.6
5.4
20.3
25.7
47.9
(Australian lizard)
Mammalia
Man 5
T
66.0
4.3
15.7
20.0
46
Camel"
T
69.8
5.3
13.9
19.2
50.6
References: ITHORSON (1959); 2THORSON (1962); 3THORSON (1961); 4BRADSHAW and
SHOEMAKER (1967); 5ELKINGTON and DANOWSKI (1955); 6 MAcFARLANE (1964) .
SW = sea-water FW = fresh water T = terrestrial
compartments thus vary in the different vertebrate groups, and THORSON (1961)
has suggested this may follow a phylogenetic pattern in the fishes.
Physical separation between the fluid compartments of the body takes place
at the cell membrane for intra- and extracellular compartments, while the walls of
the capillaries separate the intercellular and plasma phases of the latter. The skin,
and linings of the respiratory organs and gut separate the body fluids from the external environment. The volume and composition of the intracellular fluid is controlled by the cell, and more especially its outer 'plasma' membrane. The extra6