Figure 1. — Oxyhemoglobin dissociation curves 

 for three cetaceans [T. gilti. G. scammoni, E. 

 robustus). All curves have been corrected for 

 pH — 7.4 and determined at 37~C. 



percent acetic acid to iyse the red 

 cells to permit counting of a uniform 

 suspension without the problems as- 

 sociated with cells settling while being 

 counted. A standard solution was pre- 

 pared by adding a fraction of a milliliter 

 of the same solution injected into the 

 animal to saline in a total volume of 1 

 liter. The standard was prepared for 

 counting by the same procedure as the 

 blood specimens. 



All samples were counted for 100 

 minutes in a 3-inch well Til crystal 

 attached to a Packard Model 2001 

 Spectrometer Sealer-timer. Counts of 

 the paired blood specimens were very 

 close, within 5 percent in December 

 and 3 percent in March. The reported 

 blood volumes are the mean values 

 of the respective paired samples. The 

 oxyhemoglobin dissociation curve was 

 determined on 21 January 1972. A 

 20 ml blood sample was secured from 

 a puncture of a distal brachial vein 

 the the pectoral hn. The blood was 

 immediately placed into well-heparin- 

 ized (250 units heparin per 10 ml 

 blood) plastic test tubes, inverted 4 or 

 5 times, and then placed in an ice bath. 



Less than 4 hours after collection 

 the dissociation curve was completed 

 by a Dissociation Curve Analyzer 

 (DCA-1. Radiometer, Copenhagen). 

 Duvelleroy et al. (1970) have ex- 

 plained in detail the methodologs in- 

 volved in the operation and construc- 



tion of the 02-Hb dissociation curves 

 by the DCA-1. Slight changes in pH 

 were monitored for every point on 

 the dissociation curve. Because Pqo 

 changes with pH variation, corrections 

 were made to a pH of 7.4 with the 

 equation 



AlogPp^ 

 ApH 



Bohr effect. 



The value for the Bohr effect was 

 obtained from Lenfant ( 1969). 



The hematocrit (Hct) was obtained 

 in the usual manner. A Clay-Adams 

 Autocrit Centrifuge was the instrument 

 used. 



RESULTS 



The hematocrit, blood volume, and 

 Pjo of the E. robitsius as well as cer- 

 tain physiological blood parameters 

 of other cetaceans are presented in 

 Table 1. The blood volume was deter- 

 mined on two occasions and the oxy- 

 gen binding capacity was determined 

 with one blood sample. Typical sig- 

 moid Oo-Hb dissociation curves are 

 shown in Figure 1. Curves for two 

 other cetaceans. Glohicephalci scani- 

 luoni and Tiirsiops i;illi, determined 

 by the same methods (Antonelis. 1972)-' 

 are included. 



DISCUSSION 



The hematocrit of Gigi is not un- 

 like that measured in other mammals. 

 While Lenfant (1969) asserts that this 

 is true for all marine mammals. Ridg- 

 way and Johnston (1966). Horvath et 

 al. (1968). and Ridgway et al. (1970), 

 have demonstrated an increased packed 

 cell volume in some of the small 

 cetacea. Lenfant (1969) attributes 

 such results to differences in technique 

 or in physical condition. However, 

 the animals who showed high hemat- 

 ocrits were maintained in captivity. 

 Had they followed the normal pat- 



^ Antonelis, G A. 1972 Oj-Hb dissociation 

 curves of the pilot whale. Globicephala scam- 

 mom, and Pacific bottlenose porpoise, Tursiops 

 gilti- (Unpubl manuscr,} 



tern of captive animals, the values 

 would have been even higher if sampled 

 in their natural environment. It has 

 been amply demonstrated that animals 

 brought into a captive situation soon 

 show a reduction in both hetnatocrit 

 and hemoglobin content (Gilmartin 

 and Ridgway, 1969,^* Lenfant, 1969). 



The first blood volume for a large 

 cetacean using isotopic methods is 

 reported. Although H^i labeled hu- 

 man serum albumin was used in the 

 analysis, the similarity of the paired 

 blood specimens taken at each test 

 date indicates not only that mixing 

 was complete, but also that this foreign 

 protein was not being eliminated so 

 rapidly that a meaningful blood vol- 

 ume determination could not be made. 

 Unpublished data on the killer whale 

 are included also. Both animals have 

 blood volumes (£. rohusuis: 6.1 and 

 8.1 percent; O. onu: 8.2 percent) 

 within the range reported for other 

 species of large cetaceans; Laurie 

 (1933) reported a large blue whale's 

 blood volume as 6.6 percent. Smith 

 and Pace (1971) estimate that the 

 blood and body fluids of large ceta- 

 ceans to be between 10 and 15 percent 

 of the body mass. 



Lawson { 1962) and Sjiistrand ( 1953, 

 1962) have reviewed the many factors 

 which affect blood volume and one 

 should be aware of them when evaluat- 

 ing blood volume data. Since the 

 animal is placed under highly stressful 

 conditions as well as the imposition 

 of unaccustomed gravitational forces 

 as a result of removal from the water, 

 the picture for marine mammals is 

 complicated. 



Nutrition and electrolyte balance 

 also affect blood volume. To our 

 knowledge neither the freezing point 

 depression nor the osmolality of the 

 urine were determined. Osmolality 

 can be calculated, however, using the 

 formulas of Wolf (1958). Gigi's ex- 

 clusive squid diet must have produced 

 a urine whose minimum osmotic con- 



3 Gilmartin, W G, and S H Ridgway 1969 



Some physiological properties of the blood of 



the killer whale, Orcinus orca- (Unpubl, 

 manuscr ) 



29 



