OBSERVATIONS OF BLOOD VALUES, HEART-RATE AND RESPIRATORY RATE OF LEOPARD SEALS (HYDRURGA-LEPTONYX) (CARNIVORA, PHOCIDAE)

There are few opportunities to study leopard seals (Hydrurga leptonyx) under controlled conditions, and practical constraints make physiolog ical investigations of measurement in free-living animals difficult. W e examined blood characteristics, the degree of bradycardia during unr estrained submergence, and the duration of terrestrial apnea, in two c aptive leopard seals. Blood was taken from two resting, unrestrained l eopard seals out of water on nine occasions, over a period of a year. Haematocrit, mean erythrocyte count, mean corpuscular volume, haemoglo bin concentration, mean corpuscular haemoglobin and mean corpuscular h aemoglobin concentration were measured, as well as bicarbonate, pH, an d oxygen and carbon dioxide tension. Heart rate was recorded on land a nd during unrestrained submergence; the mean degree of bradycardia on submergence was 27%, maximum 44%. Periods of terrestrial apnea, which have been shown to increase as diving capacity increases during ontoge ny in northern elephant seals, were of shorter duration in the leopard seals than in captive harbour seals or southern elephant seals. It is postulated that this is indicative of lesser diving ability of leopar d seals than the other two species.