Observations of Blood Values, Heart-Rate and Respiratory Rate of Leopard Seals (Hydrurga-Leptonyx) (Carnivora, Phocidae)

Abstract

There are few opportunities to study leopard seals (Hydrurga leptonyx) under controlled conditions, and practical constraints make physiological investigations of measurement in free-living animals difficult. We examined blood characteristics, the degree of bradycardia during unrestrained submergence, and the duration of terrestrial apnea, in two captive leopard seals. Blood was taken from two resting, unrestrained leopard seals out of water on nine occasions, over a period of a year. Haematocrit, mean erythrocyte count, mean corpuscular volume, haemoglobin concentration, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration were measured, as well as bicarbonate, pH, and oxygen and carbon dioxide tension. Heart rate was recorded on land and 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 ontogeny 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 leopard seals than the other two species.