Table 7.2 Osmot ic constitue nts in the plasma of various fishes
Habitat
Sodium
Potassium
Urea Osmolarit y
m-equiv /I m-equ iv / I
mM m-osmole/I
Sea-water
470
12
1070
Osteichthyes
Latim eria cbalumnae!
SW',
181
355
1181
(Coel acanth)
Protop terus aetb iopi cust
FW·
99
8
238
(Afr ican lungfish)
Carassius auratus 3
FW
115
3.6
259
(Goldfish)
Ops anus tau"
SW
160
5.2
392
(Toadfish)
Platichthy s flesus 5
FW
157
5
304
(Flou nder)
SW
194
5
364
Anguilla anguilla 6
FW
155
2.7
323
(European eel)
SW
177
2.8
371
Salmo salar 7
FW
181
1.9
340
(Atlantic salmon)
SW
212
3.2
400
Chondrichthyes
Raja claoata"
SW
289
4
444
1050
(Th orn back ray)
Squalu s acanth ias". 10
SW
287
5.4
354
1000
(Spiny dogfish)
Chimaera montrosai
SW
360
10
265
(Rabbitfish)
Pristis microdo n'!
FW
170 (Cl)
130
540
(Freshwater sawfish)
Agnatha
Myxine glutino sa
12
SW
549
11
1152
(H agfish)
Lamp reta fluviatilis 13
FW
120
3
270
(River lamprey)
"' SW = sea-water ; FW = fresh water
Referen ces: IPICKFORD and GRANT (1967); 2SM1TH (1930 a)
3MAETZ (1963); 4LAHLOU, HENDERSON, and SAWYER (1969 b); 5LANGE and FUGELL! (1965);
6SHARRATT, CHESTER J ONES, and BELLAMY (1964 a) ; 7PARRY (1961); 8Mu RRAY and POTTS
(1961); 9FANGE and FUGELLI (1962); lOB URGER (1965); llSMITH (1936); 12BELLAMY and
CHESTER JONES (1961); 13RoBERTSON (1954).
chondrichthyeans constitutes about 5% of their bod y weight, which is similar to
that of the tetrapods, but in oste ichthyeans it is, according to THORSON (1961),
about half as large. However, as the number of species of bon y fishes is vast and
the measurements have been made on comparatively few, it remains to be seen
whether such a difference is a general characterist ic of these animals.
201